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

[EX Q]: Problem: what is the probability of getting a queen or spade from a set of cards ?
[EX A]: 4 / 13

[EX Q]: Problem: how many positive integers less than 20 can be expressed as the sum of a positive multiple of 2 and a positive multiple of 3 ?
[EX A]: 14

[EX Q]: Problem: a cement mixture is composed of 3 elements . by weight , 1 / 2 of the mixture is sand , 1 / 5 of the mixture is water , and the remaining 15 pounds of the mixture is gravel . what is the weight of the entire mixture in pounds ?
[EX A]:
50