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: what is the rate percent when the simple interest on rs. 720 amount to rs. 180 in 4 years ?
Options: a. 6.25, b. 7.25, c. 8.25, d. 9.25, e. 10.25
[EX A]: a

[EX Q]: Problem: when a certain number x is divided by 61, the remainder is 24. what is the remainder when x is divided by 5 ?
Options: a. 2, b. 3, c. 4, d. 5, e. 6
[EX A]: c

[EX Q]: Problem: a and b can together finish a work in 40 days. they worked together for 10 days and then b left. after another 15 days, a finished the remaining work. in how many days a alone can finish the job ?
Options: a. 10, b. 25, c. 60, d. 30, e. 20
[EX A]:
e