instruction:
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.
question:
Problem: if the average ( arithmetic mean ) of a and b is 45 and the average of b and c is 80, what is the value of c a ?
Options: a. 25, b. 60, c. 90, d. 140, e. it can not be determined from the information given.
answer:
b

question:
Problem: a movie buff buys movies on dvd and on blu - ray in a ratio of 13: 4. if she returns 2 blu - ray movies, that ratio would change to 7: 2. if she buys movies on no other medium, what was the original number of movies purchased ?
Options: a. 22, b. 28, c. 77, d. 99, e. 119
answer:
e

question:
Problem: of the 100 employees at company x, 80 are full - time, and 100 have worked at company x for at least a year. there are 20 employees at company x who aren ' t full - time and haven ' t worked at company x for at least a year. how many full - time employees of company x have worked at the company for at least a year ?
Options: a. 20, b. 30, c. 50, d. 80, e. 100
answer:
a