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

[Q]: Problem: the ratio of a to b is 4 to 5 , where a and b are positive . if x equals a increased by 25 percent of a , and m equals b decreased by 60 percent of b , what is the value of m / x ?
[A]: 2 / 5

[Q]: Problem: what is the sum of the odd integers from 55 to 75 , inclusive ?
[A]: 71

[Q]: Problem: before 7 years , dog a ' s age was 4 times of dog b ' s age and after 4 years , dog a ' s age will be 3 times of dog b ' s age . what is the difference of dog a ' s age and dog b ' s now ?
[A]:
7