Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: the total age of a and b is 15 years more than the total age of b and c. c is how many year younger than
Options: a. 14 years, b. 12 years, c. 56 years, d. 66 years, e. 15 years
e

Problem: what is the smallest number by which 2880 must be divided in order to make it into a perfect square ?
Options: a. 3, b. 4, c. 5, d. 6, e. 7
c

Problem: a certain company had a total annual expenditure of 1.26 ∗ 10 ^ 7 on employee salaries last year. if the company employed 420 people, what was the average employee salary ?
Options: a. $ 20,000, b. $ 25,000, c. $ 35,000, d. $ 30,000, e. $ 45,000

d