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: 2,7 , 17,3 , 11,19 , 5,13 , __
23

Problem: a and b together can complete work in 6 days . a alone starts working and leaves it after working for 4 days completing only half of the work . in how many days it can be completed if the remaining job is undertaken by b ?
12