SOLUTION: Robert can paint a room in 12 hours. Dennis and Vince can paint the room in 10 hours and 9 hours, respectively. If Dennis and Vince work together for 2 hours, how long will it tak

Question 989011: Robert can paint a room in 12 hours. Dennis and Vince can paint the room in 10 hours and 9 hours, respectively. If Dennis and Vince work together for 2 hours, how long will it take Robert to finish the job?

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Robert can paint a room in 12 hours. Dennis and Vince can paint the room in 10 hours and 9 hours, respectively. If Dennis and Vince work together for 2 hours, how long will it take Robert to finish the job?
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Robert rate:: 1/12 job/hr
Dennis rate:: 1/10 job/hr
Vince rate:: 1/9 job/hr
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time*rate = work done
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2(1/10 + 1/9) = 2(19/90) = 19/45 job done by D and V together
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(1/12)x = 1 - (19/45)
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(1/12)x = 26/45
x = 12*26/45
x = 6.93 hours (time for Robert to finish the job)
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Cheers,
Stan H.
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