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

[EX Q]: Problem: a is half good a work man as b and together they finish a job in 14 days . in how many days working alone b finish the job ?
[EX A]: 21

[EX Q]: Problem: a , b , c , d , e , f , g , h sitting in a row what is the probability that a , b , c sitting together ?
[EX A]: 3 / 28

[EX Q]: Problem: how many three - element subsets of { 1,2 , 3,4 } are there that do not contain the pair of elements 2 and 4 ?
[EX A]:
2