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

[Q]: Problem: if 5 a = 3125 , then the value of 5 ( a - 3 ) is :
[A]: 25


[Q]: Problem: the h . c . f of two numbers is 23 and the other two factors of their l . c . m are 14 and 15 . the larger of the two numbers is :
[A]: 345


[Q]: Problem: the average age of 15 students of a class is 15 years . out of these , the average age of 6 students is 14 years and that of the other 8 students is 16 years . the age of the 15 th student is
[A]:
13 years