A person decided to build a house in 100 days. He employed 100 men in the beginning and 100 more after 20 days and completed the construction in stipulated time. If he had not employed the additional men , how many days behind schedule would it have been finished? Choose the correct choice from the following options:
A) 40
B) 80
C) 70
D) 60
E) 50

Rationale: "200 men do the rest of the work in 100 - 20 = 80 days 100 men can do the rest of the work in 80 * 200 / 100 = 160 days required number of days = 160 - 80 = 80 days answer is b"
Answer: B