If A and B work together,they can finish a task in 2 hours. If they do the task separately, B can finish 3 hours earlier than A can. Find the time required for B to finish the task alone.

Answer 1

Recall that if A takes A hours, and B takes B hours,

1/A + 1/B = 1/2

So, if B does the task in x hours, A takes x+3 hours:

1/(x+3) + 1/x = 1/2

Now just solve for x.