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Question 184281: We are studying rational expressions and I was asked to solve this problem. Please help!!!
Let's say it takes me 6 hours to paint a house, and it takes you 5 hours to paint it. How long will it take us to paint it working together?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Let's say it takes me 6 hours to paint a house, and it takes you 5 hours to paint it. How long will it take us to paint it working together?
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You wouldn't want to add the times because if you can do it in 5 hours it
should not take 5+6 = 11 hours if you had help.
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So, what you do in find the rates and you add them:
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Me DATA:
time = 6 hrs/job ; rate = 1/6 job/hr
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You DATA:
time = 5 hrs/job ; rate = 1/5 job/hr
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Together DATA:
time = x hrs/job ; rate = 1/x job/hr
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Equation:
rate + rate = together rate
1/6 + 1/5 = 1/x
Multiply thru by 30x to get:
5x + 6x = 30
11x = 30
x = 30/11 hours (time it would take you and me working together)
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Cheers,
Stan H.
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