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.

[EX Q]: Problem: micheal and adam can do together a piece of work in 20 days. after they have worked together for 15 days micheal stops and adam completes the remaining work in 10 days. in how many days micheal complete the work separately.
Options: a. 40 days, b. 100 days, c. 120 days, d. 110 days, e. 90 days
[EX A]: a

[EX Q]: 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
[EX A]: e

[EX Q]: Problem: the bankers discount of a certain sum of money is rs. 288 and the true discount on the same sum for the same time is rs. 240. the sum due is :
Options: a. 1400, b. 1420, c. 1440, d. 1460, e. 1480
[EX A]:
c