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

Problem: if x , y , and z are positive integers , and 3 x = 5 y = 6 z , then the least possible value of x + y + z is
21

Problem: the average of first 17 even numbers is ?
18

Problem: the average of 5 consecutive odd numbers is 55 . what is the difference between the highest and lowest numbers ?

8