Go: package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextFloat64() (float64, error) {
	return strconv.ParseFloat(nextString(), 64)
}

func mathRound(f float64) float64 {
	return math.Floor(f + .5)
}

func round(x float64) float64 {
	if math.Abs(x) < 0.001 {
		return 0
	}
	return mathRound(x*1000) / 1000
}

func main() {
	scanner.Split(bufio.ScanWords)
	for {
		a, err := nextFloat64()
		if err != nil {
			break
		}
		b, _ := nextFloat64()
		c, _ := nextFloat64()
		d, _ := nextFloat64()
		e, _ := nextFloat64()
		f, _ := nextFloat64()

		detA := a*e - b*d
		x := (c*e - b*f) / detA
		y := (a*f - c*d) / detA

		fmt.Printf("%.3f %.3f\n", round(x), round(y))
	}
}

C++: #include <iomanip>
#include <iostream>
#include <vector>
#define N 2
 
using namespace std;
typedef vector< vector<double> > Equation;
 
int main()
{ 
    Equation c(N, vector<double>(N + 1));
	while (cin)
	{
		// input
		for (int i = 0; i < N; ++i)
			for (int j = 0; j < N + 1; ++j)
				cin >> c[i][j];

		// Gaussian elimination
		// 1. Forward elimination
        for (int i = 0; i < N - 1; ++i)
            for (int j = i + 1; j < N; ++j)
            {
                double d = c[j][i] / c[i][i];
                for (int k = i + 1; k <= N; ++k)
                    c[j][k] -= c[i][k] * d;
            }
 
		// 2. Back substitution
        for (int i = N - 1; i >= 0; --i)
        {
            double d = c[i][N];
            for (int j = i + 1; j < N; ++j)
                d -= c[i][j] * c[j][N];
            c[i][N] = d / c[i][i];
        }
 
		for (int i = 0; i < N; ++i)
			if (c[i][N] < -0.001)
				c[i][N] = 0;

        cout << setprecision(3) << fixed << c[0][N];
        for (int i = 1; i < N; ++i)
            cout << " " << c[i][N];
        cout << endl;
    }
 
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-10;

int main() {
    double a, b, c, d, e, f;
    while(cin >> a >> b >> c >> d >> e >> f){
        printf("%.3lf %.3lf\n",round((b*f-c*e)/(b*d-a*e)*1000)/1000+EPS,round((c*d-a*f)/(b*d-a*e)*1000)/1000+EPS);
    }
    return 0;
}

C++: #include <stdio.h>
#include <math.h>

int main(){
  int i = 0;
  int a, b, c, d, e, f;

  while(scanf("%d", &a)!=EOF){
  i++;
  scanf("%d ",&b);
  scanf("%d ",&c);
  scanf("%d ",&d);
  scanf("%d ",&e);
  scanf("%d ",&f);
  
  double x, y;
  x = (double)(c*e-b*f) / (double)(a*e-b*d);
  y = (double)(a*f-c*d) / (double)(a*e-b*d);
  x = (double)round(x*10000.0) / 10000.0;
  y = (double)round(y*10000.0) / 10000.0;
  printf("%.3f %.3f\n", x, y);
  
  }
  return 0;
}

C++: #include "bits/stdc++.h"
#include <gmp.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> veci;
typedef vector<ll> vecll;
typedef vector<string> vecs;
template<class T,class U> using Hash=unordered_map<T,U>;

#define REP(i, a, n) for(ll i = a; i < (ll)n; i++)
#define RREP(i, a, n) for(ll i = n-1; i >= (ll)a; i--)
#define rep(i, n) REP(i, 0, n)
#define rrep(i, n) RREP(i, 0, n)
#define MD 1000000007

template<class T> T read(){T a;cin >> a;return a;}
template<class T> void read(T& a){cin >> a;}
template<class T, class ...Args> void read(T& a, Args&... args){cin >> a; read(args...);} 
template<class T> void rarr(T a, int n){for(int i = 0; i < n; i++) {cin >> a[i];}}
template<char c = ' ',class T> void write(T a){cout << fixed << setprecision(4) << a << endl;}
template<char c = ' ',class T,class ...Args> void write(T a, Args... args){cout << fixed << setprecision(4) << a << c; write<c>(args...);}
template<class T> void warr(vector<T> a, const char* c = " "){cout << a[0];for(int i = 1; i < (int)a.size(); i++)cout << c << a[i];cout << endl;;}
template<class T> void warr(T a, int n, const char* c = " "){cout << a[0];for(int i = 1; i < n; i++)cout << c << a[i];cout << endl;}
void split(string s, string delim, veci& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(atoi(s.substr(pos).data()));break;}else {result.push_back(atoi(s.substr(pos, p - pos).data()));}pos = p + delim.size();}}
void split(string s, string delim, vecs& result){result.clear();string::size_type pos = 0;while(pos != string::npos){string::size_type p = s.find(delim, pos);if(p == string::npos){result.push_back(s.substr(pos));break;}else {result.push_back(s.substr(pos, p - pos));}pos = p + delim.size();}}
ll gcd(ll a, ll b){while(true){ll k = a % b;if(k == 0)return b;a = b;b = k;}}
ll comb(ll n, ll m){ll p=1;m=min(m,n-m);for(ll i=1;i<=m;i++){p*=n-i+1;p/=i;}return p;}

int main(void)
{
    while(!cin.eof()){
        double a[6];
        rep(i,6)cin>>a[i];
        double b[3];
        double p=a[0]/a[3];
        rep(i,3)b[i]=a[i]-a[i+3]*p;
        double resb=b[2]/b[1];
        double resa=(a[2]-a[1]*resb)/a[0];
        resb=floor(resb*1000)/1000.0;
        resa=floor(resa*1000)/1000.0;
        write(resa,resb);
    }
    return 0;
}

C++: #include <iostream>
#include <vector>
#include <map>
 
using namespace std;
 
int main()
{
  int a,b,c,d,e,f;
  double A[2][2];
  double B[2];
  double inv_A[2][2];
  while(~scanf("%d %d %d %d %d %d",&a,&b,&c,&d,&e,&f)){
    int det = a*e-b*d;
    A[0][0]=a; A[0][1] = b;
    A[1][0]=d; A[1][1] = e;
    B[0] = c;
    B[1] = f; 
 
    inv_A[0][0]=A[1][1]; inv_A[0][1]=-A[0][1];
    inv_A[1][0]=-A[1][0]; inv_A[1][1]=A[0][0];
 
    double res[2];
    res[0]=0;
    res[1]=0;
 
    for(int j=0;j<2;j++){
      for(int k=0;k<2;k++){
	res[j]+=1.0/(double)det *inv_A[j][k]*B[k];
      }
    }
 
    printf("%.3f %.3f\n",res[0],res[1]);
  }
}

C++: #include <iostream>
#include <utility>
using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.setf(ios::fixed);
    cout.precision(3);
    double a, b, c, d, e, f;
    while(cin>>a>>b>>c>>d>>e>>f) {
        cout<<(c*e-b*f)/(a*e-b*d)+0<<' '<<(a*f-c*d)/(a*e-b*d)+0<<'\n';
    }
    return 0;
}

C++: #include <iostream>
#include <cstdio>

using namespace std;

int main()
{
	int a, b, c, d, e, f, ny, li, ac, dc;
	double x, y;

	while (cin >> a >> b >> c >> d >> e >> f){
		ac = a;
		dc = d;
		a *= dc;
		b *= dc;
		c *= dc;
		d *= ac;
		e *= ac;
		f *= ac; 		
		ny = b - e;
		li = c - f;
		y = li / ny;
		x = (c - b * y) / a;		

		printf("%.3f %.3f\n", x + 0.0, y);
	}
	return (0);
}

C++: #include<iostream>
#include<cstdio>

using namespace std;

double round(double d){
	int k = (int)(d*10000)%10;
	int k2 = (int)(d*100000)%10;
	int k3 = (int)(d*1000000)%10;
	int k4 = (int)(d*10000000)%10;
	return (k>=5 || k == 4 && k2 >= 8 && k3 >= 8)? d-((double)k/10000)+0.001: d- ((double)k/10000);
}

int main(){
	int a, b, c, d, e, f;

	while(cin >> a >> b >> c >> d >> e >> f){
		double del = 1.0/(a*e - d*b);
		printf("%0.3f %0.3f\n", round(del*(e*c-b*f)), round(del*(a*f-d*c)));
	}
}

C++: #include <stdio.h>

int main (void){
	int a, b, c, d, e, f;
	double ans[2];
	while(scanf("%d%d%d%d%d%d", &a, &b, &c, &d, &e, &f)!=EOF){
		ans[0]=(double)(b*f-c*e)/(d*b-a*e);
		ans[1]=(double)(c*d-a*f)/(b*d-a*e);
		printf("%.3lf %.3lf\n", ans[0], ans[1]);
	}
	return 0;
}