Question

Sally can paint the wall in 54 minutes. If Sally and Ethan work together, they can paint the wall in 36 minutes. How much time does it take for Ethan to paint the wall by herself?

Answer 1

`108\ minutes`

Explanation:

1) we know that

Sally can paint the wall in 54 minutes

so

The 100% of the wall ------> she can paint in 54 minutes

by proportion

calculate how much is the percent of the work in 36 minutes

`(100\%)/(54) =(x\%)/(36)\\ \\x=36*100/54\\ \\x=66.67\%`

That means

Sally in 36 minutes can paint the 66.67% of the wall

2) Sally and Ethan work together, they can paint the wall in 36 minutes

so

Ethan in 36 minutes can paint (100%-66.67%)=33.33%

by proportion

Calculate how much time does it take for Ethan to paint the wall by herself

`(33.33\%)/(36) =(100\%)/(x)\\ \\x=36*100/33.33\\ \\x=108\ minutes`