Kraig376
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# SAT Help 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?

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)