how long would it take them to wash the walls working together?

Question

sara can wash the walls in 3 hours working alone, and tom can wash the walls in 2 hours. to the nearest tenth of an hour how long would i take them to wash the walls working together?

Answer 1

time together/time alone + time together/time alone = 1

Let t = the time it will take them working together

t/3 + t/2 = 1

Multiply both sides by 6.

2t + 3t = 6

5t = 6

t = 6/5

t = 1.2 hours