One student can paint a wall in 20 minutes. Another student can paint the same wall in 30 minutes. Working together, how long will it take for them to paint the wall?

Answer 1

The first student can paint 1/20 of the wall per minute.

The second student canpaint 1/30 of the wall per minutes.

Working together they paint 1/20 + 1/30 = 50/600 = 1/12 of the wall per minute.

It will take the 12 minutes