Question

A can do a piece of work in 20 days and B in 15 days. They worked together on it for 6 days and then A left. How long will B take to finish the remaining work?

Answer 1

Given,

A can do a piece of work in = 20 days

B can do a piece of work in = 15 days

∴ A's 1-day work =`1/20`

B's 1-day work = `1/15`

(A+B)'s 1-day work =`1/20+1/15`

`=(3+4)/60=7/60`

(A+B)'s 6 days work =`7/60xx6=7/10`

Remaining work =`1-7/10`

`=(10-7)/10=3/10`

B can do 1 work in = 15 days

B can do `3/10` work in =`15xx3/10` days

`=45/10`days =`9/2` days = `4 1/2` days