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

Problem: 5 years ago , paula was 3 times as old as karl . in 6 years , paula will be twice as old as karl . what is the sum of their ages now ?
54

Problem: the ratio between b and y is 7 / 9 ; b and y are increased by 4 , what is the ratio between the new values of b and y ?
it can not be determine

Problem: what is the rate percent when the simple interest on rs . 800 amount to rs . 160 in 5 years ?

4