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 y exceeds x by 25 %, then x is less than y by ?
Options: a. 28 %, b. 21 %, c. 20 %, d. 30 %, e. 29 %

Answer: c

Question: Problem: sakshi can do a piece of work in 5 days. tanya is 25 % more efficient than sakshi. the number of days taken by tanya to do the same piece of work :
Options: a. 4, b. 16, c. 18, d. 25, e. 10

Answer: a

Question: Problem: when the price of a product was decreased by 20 %, the number sold increased by 60 %. what was the effect on the total revenue ?
Options: a. 28 %, b. 32 %, c. 35 %, d. 45 %, e. 52 %

Answer:
a