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

[EX Q]: Problem: a is twice as good a workman as b and they took 6 days together to do the work b alone can do it in .
[EX A]: 18 days

[EX Q]: Problem: twice the larger of two numbers is 3 more than 5 times the smaller , and the sum of 4 times the larger and 3 times the smaller is 71 . what are the numbers ?
[EX A]: 14

[EX Q]: Problem: a crow leaves its nest , and flies back and forth from its nest to a nearby ditch to gather worms . the distance between the nest and the ditch is 250 meters . in one and a half hours , the crow manages to bring worms to its nest 15 times . what is the speed of the crow in kilometers per hour ?
[EX A]:
5