Google - al washes a car in 6 minutes Sara washes a car in 8 minutes how long does it take them?

Nmin x (1car/6min + 1car/8min) = 1car Put the units right into the equation and treat them with normal algebra so you can be sure they cancel and leave a correct answer. We have min above the fraction bar and again below, so that cancels. We have car above the fraction bar and that appears in the answer like we want it. Now multiply by all the numbers above the bar and divide by all the numbers below.

N x (1/6 + 1/8) = 1

N/6 + N/8 = 1 Multiply everything by 48.

8N + 6N = 48

14N = 48 Divide by 14.

N = 24/7 min <<-- ANSWER