Detailed Instructions: 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: a contractor undertakes to built a walls in 50 days. he employs 40 peoples for the same. however after 25 days he finds that only 40 % of the work is complete. how many more man need to be employed to complete the work in time ?
Options: a. 60, b. 30, c. 35, d. 20, e. none of these
Solution:
a