Question

Karen can paint a wall in 2.5 hours. Stephanie takes 1.25 hours to paint the same size wall. How many minutes will it take for Karen and Stephanie working together to paint the same wall?

Answer 1

If Karen takes 2.5 hours to paint the whole wall, then in an hour she paints a fraction of 2/5.
On the other hand, if Stephanie takes 1.25 hours then in an hour she paints a fraction of 4/5 of the wall.
When the two are working together then one hour they will paint a fraction of  6/5 of the wall. But the wall is one whole therefore it will take 5/6 hours or 50 minutes for them to paint the whole wall together. The answer is 50 minutes