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

Ex Input:
Problem: a man is 28 years older than his son . in two years , his age will be twice the age of his son . the present age of the son is ?

Ex Output:
26


Ex Input:
Problem: bob wants to run a mile in the same time as his sister . if bob ’ s time for a mile is currently 11 minutes 20 seconds and his sister ’ s time is currently 9 minutes 36 seconds , by what percent does bob need to improve his time in order run a mile in the same time as his sister ?

Ex Output:
15 


Ex Input:
Problem: in the x - y plane , there are 4 points ( 0,0 ) , ( 0,4 ) , ( 8,4 ) , and ( 8,0 ) . if these 4 points makes a rectangle , what is the probability that x + y < 4 ?

Ex Output:

1 / 4