X and Y together can finish a task in 12 days. If Y alone can finish the same task in 15 days, then how many days will X alone take to finish the task?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 60.
X + Y together: 1/12 work per day
Y alone: 1/15 work per day
So, X’s 1 day work = 1/12 − 1/15 = (5−4)/60 = 1/60
⇒ X alone takes 60 days