A and B together can complete a task in 12 days. However, if A works alone, completes
half the job and leaves and then B works alone and completes the rest of the work, it takes 25 daysin all to complete the work. If B is moreefficient than A, how many days wouldit have taken B to do the work by herself?

Let A took 'A' days to complete the task and B took 'B' days

then Total time taken = $$\frac{AB}{A+B}$$=12 ------------ Equation (i)

However, A alone taken time = 'A' days will be $$\frac{A}{2}$$ days.

Same for B alone taken time = 'B' days will be $$\frac{B}{2}$$ days.

Total Time = $$\frac{A}{2}$$ + $$\frac{B}{2}$$ = 25 days.

A+B= 50 days -------------------- Equation (ii)

By (i) and (ii) equation AB = 600 ----------------- Equation (iii)

A,B =20,30

Because B is more efficient takes less days 80.

A,B,C = 2,8,8