Question

A and B can do a piece of work in 20days and 12 days respectiively. A started the work al NMone and then after 4days B joined him till the completion of the work. How long did the work last?

Answer 1

A and b complete work in 20 and 12 days.

Let total work is 60 unit.

Than a does 3 units per day and b does 5 units per day.

A works 4 day alone than he will do 12 units .

Remain unit of work. 60-12=48

A and b work together 8 unit per day

Than 48 unit work completed in 6 days. And total work completed in 10 days.