A is thrice as efficient as B and hence completes a work in 40 days less than the number of days taken by B. What will he the number of days taken by both of them when working together?

A) 22.5 days

B) 15 days

C) 20 days

D) 18 days

Correct Answer:

B) 15 days

Description for Correct answer: A is thrice efficient as B

Let total unit of work to be done is x unit

Now according to question

\( \Large \frac{x}{3} = x - 40 \)

x = 3x - 120

2x = 120

x = 60

Number of days taken by both of them to 60 complete the work = \( \Large \frac{60}{4} \)= 15 days