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

[EX Q]: Problem: find the principle on a certain sum of money at 9 % per annum for 2 2 / 5 years if the amount being rs . 1120 ?
[EX A]: 921.0

[EX Q]: Problem: how many diagonals does a polygon with 13 sides have , if one of its vertices does not connect to any diagonal ?
[EX A]: 54

[EX Q]: 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 A]:
26