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Jack can paint a house in 5 days, and Richard can paint the same house in 7 days. Working together, how long will it take them to finish the job? In 7*5 = 35 days, Jack can paint 7 houses. Here's a similar problem: There are two small holes in a tub filled with water. If opened, one hole will empty the tub in 3 hours; the other will empty it in 6 hours. If both holes are opened at the same time, how long will it take to empty the tub? One hole will empty the tub in 3 hours; so in 6*3 hours, it would empty 6 tubs. ## From the Dr. Math archives:-
Combining Rates of Work (I)
Combining Rates of Work (II) Leaky Ship Ratio and Proportion Ratio and Proportion: Jobs Ratio of Rates and Work Sergeant Marco's Maintenance Check A Simple Formula? Simultaneous Equations A Time-Rate Problem Word Problem with Fractions Filling a Pool Filling a Tank Two Pipes and a Drain |

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