SOLUTION: If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together? I have several question

Algebra ->  Expressions-with-variables -> SOLUTION: If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together? I have several question      Log On


   

Question 188134: If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?
I have several question like this and don't know how to set it up.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?
I have several question like this and don't know how to set it up.
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Sally DATA:
Time = 4 hr/job ; rate = 1/4 job/hr
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John DATA:
Time = 6 hr/job ; rate = 1/6 job/hr
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Together DATA:
Time = x hr/job ; rate = 1/x job/hr
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Equation:
rate + rate = together rate
1/4 + 1/6 = 1/x
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Multiply thru by 12x to get:
3x + 2x = 12
5x = 12
x = 12/5 hr or 2 hr and 24 minutes
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Cheers,
Stan H.