Question

one student can paint a wall in 10 minutes. another student can paint the same wall in 15 min. working together, how long will it take for them to paint the wall

Answer 1

6 minutes

Explanation:

Formula

1/15 + 1/10 = 1 / x where x is the time it takes both of them to do the job.

Solution

The lowest common denominator for 1/15 and 1/10 is 30

2/30 + 3/30 = 1/x

5/30 = 1/x Cross multiply

5x = 30 Divide by 5

5x / 5 = 30/5

x = 6