Question from IT foundation. A, B, and C can do a work in 20, 45, and 120 days,respectively. They started the work. A left 10 daysbefore and B left 5 days before the completion ofwork. In how many days is the total work completed?

If N is the total time taken, it means that

A worked for (N -10) days, B for (N - 5) days

and C for N days.

Hence (N - 10) * 1/20 + ( N - 5)*1/45 +

N/120 = 1

(N - 10) * 18 + ( N -5)* 8 + 3 N = 360

18 N - 180 + 8N - 40 + 3 N = 360

29N = 580

N = 20