The task is to generate the correct answer for a given math problem.

[Q]: Problem: find ( 7 x + 2 y ) / ( x - 2 y ) if x / 2 y = 3 / 2 ?
[A]: 23

[Q]: Problem: a car salesman earns a base salary of $ 1000 per month plus a commission of $ 200 for each car he sells . if the car salesman earned $ 2000 in march , how many cars does he need to sell in april in order to double his march earnings ?
[A]: 15

[Q]: Problem: the total age of a and b is 12 year more than the total age of b and c . c is how many years younger than a ?
[A]:
12