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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?


How do you solve this?

Verified Answer :

Well, their speeds are (\(V_1\) is Jack's speed, and \(V_2\) is Richard's.
\(V_1 = \frac{1}{5} houses/day \\ V_2 = \frac{1}{7} houses/day \\ V = V_1 + V_2 = \frac{1}{5}+\frac{1}{7} = \frac{7+5}{35} = \frac{12}{35}\)
They, together, can paint 12 houses in 35 days. To get a single house, we only have to calculate \(\frac{35}{12}\) which is very close to 3 (a bit below)

MNewberry359

Answer:

In 75 = 35 days, Jack can paint 7 houses.

In 57 = 35 days, Richard can paint 5 houses.

So in 35 days, the two of them can paint 12 houses. To paint just one house, they'll need 1/12 the time, or 35/12 = 2 11/12 days.

Step-by-step explanation:

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