TASK DEFINITION: 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: Problem: the average weight of a group of persons increased from 48 kg to 51 kg, when two persons weighing 78 kg and 93 kg join the group. find the initial number of members in the group ?
Options: a. 87, b. 67, c. 23, d. 75, e. 25

SOLUTION: c

PROBLEM: Problem: virginia, adrienne, and dennis have taught history for a combined total of 96 years. if virginia has taught for 9 more years than adrienne and for 12 fewer years than dennis, for how many years has dennis taught ?
Options: a. 23, b. 32, c. 35, d. 41, e. 42

SOLUTION: e

PROBLEM: Problem: joan took out a mortgage from hel local bank. each monthly mortgage payment she makes must be triple the amount of the previous month ' s payment. if her first payment is $ 100, and the total amount she must pay back is $ 914800, how many months will it take joan to pay back her mortgage ?
Options: a. 6, b. 8, c. 10, d. 9, e. 13

SOLUTION:
d