Question

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.
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.

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