SOLUTION: It takes Tom 4 hours to build a fence. If he hires Jack to help him, together they can do the job in just 3 hours. If jack built the same fence by himself, how long would it take h

Question 38574: It takes Tom 4 hours to build a fence. If he hires Jack to help him, together they can do the job in just 3 hours. If jack built the same fence by himself, how long would it take him??
Thanks for answering!:-)
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
We use the work problem formula
t/A + t/B = 1
t = time worked together
A = first guy's time alone
B = second guy's time alone
1 = one job or task
so plug in and get
3/4 + 3/B = 1
multiply all by 4B and get
3B + 12 = 4B
and
B = 12 hours
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