Question

A and B together can finish a piece of work in 12 days. If 'A' alone can finish the same work in 20 days, in how much days B alone can finish it?

Answer 1

⊕ANSWER⊕

as we know a person one day work is equal to 1/n of total work where n is number of days 

therefore a+b is equal to

1/a of the total work+1/b of the total work =1/12(as we calulate per day )

1/20+1/b of the total work =1/20 (as they gave as a alone can do in 20 days)

1/b of the total work =1/20-1/12

1/b of the total work =as LCM  is 60 we get 3-5/60

1/b of the total work=-2/60 ⇒-1/30

therefore as b one day work is 1/30 the total work is equal to 30 days

⇒b works in 30 days