Question

A and b individually can do a piece of work in 16 days and 20 days respectively. If a and b start the work simultaneously and 2 days before the completion, a left the work and then find the total days required to complete the whole work.

Answer 1

A. can do in 16 days,

in one day he does 1/16 work.

B. can do in 20 days,

in one day he can do 1/20 work.

in one day A and B does 1/16 + 1/20 = 9/80 work.

let x days is the total work duration.

we get, x-2 days of combined work and 2 days of B. work.

(x-2)*9/80 + 2/20 = 1.

equation 1.

9x-18 +8 = 80.

9x = 90

x = 10.

hence 10 days is the total work duration.

8 days of A work = 8/16

10 days of B work = 10/20

1/2 + 1/2 = 1.