154238 wrote:

A can complete a project in 20 days and B can complete the same project in 30 days. If A and B start working on the project together and A quits 10 days before the project is completed, in how many days will the project be completed?

(A) 18 days

(B) 27 days

(C) 26.67 days

(D) 16 days

(E) 12 days

Assume to total work to be 60 Units ( LCM of 20 & 30)

A does 3 units per day ( =60/20)

B does 2 units per day ( =60/30)

B works for 10 days alone work done = 2*10 = 20 units

A and B work together for the rest of the time

work left = 40 units

A and b together to 5 units oer day ( 2+3 = 5)

days required to do 40 units = 40/5 = 8

Total = 10+8 = 18