X works four times as fast as Y.Y takes 60 days more than X to complete a job. Find the time in which X and Y working together can complete the job ( in days)

Options

A. 20
B. 10
C. 16
D. 12

Answer

C

Explanation

Let the time in which X and Y can complete the job be x days days y repectively.
`(1)/(x)=4((1)/(y))" "(1)`
`y=x+60 " "(2)`
From Eq. (1), we get
`y=4x`
Substituting this value in Eq. (2) ,we get
`4x=x=60`
`x=20`
`y=80`
The time in which X and Y can complete the job (in days) `=(xy)/(x+y)=16`