Question

One student can paint a wall in 12 minutes. Another student can paint the same wall in 24minutes. Working together, how long will it take for them to paint the wall?

Answer 1

8 minutes.

Explanation:

We work in fractions of the wall they can paint in 1 minute, so

1/12 + 1/24 = 1/x where x is the time it takes when working together.

Multiplying through by 24x:

2x + 1x = 24

3x = 24

x = 8 minutes.