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

Ex Input:
Problem: a train covers a distance of 12 km in 10 minutes . if it takes 8 seconds to pass a telegraph post , then the length of the train is

Ex Output:
160 m


Ex Input:
Problem: what is the units digit of 17 ^ 83 × 13 ^ 82 × 11 ^ 67 ?

Ex Output:
4


Ex Input:
Problem: gold is 19 times as heavy as water and copper is 9 times as heavy as water . in what ratio should these be mixed to get an alloy 15 times as heavy as water ?

Ex Output:

3 : 2