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

[EX Q]: 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 ?
[EX A]: 54

[EX Q]: Problem: a cat chases a rat 6 hours after the rat runs . cat takes 4 hours to reach the rat . if the average speed of the cat is 90 kmph , what s the average speed of the rat ?
[EX A]: 36 kmph

[EX Q]: Problem: if 9 workers can build 9 cars in 9 days , then how many days would it take 7 workers to build 7 cars ?
[EX A]:
9