Jane can paint the office by herself in 7 hours. Working with an associate, she can paint the office in 3 hours. How long would it take her associate to do it working alone?

Your turn!

Step-by-step explanation:

Jane works in 7 hours. Hence in 1 hour, she will paint 1/7 of the office

Let x is the part her associate works in 1 hour.

Then in 1 hour, both them will work (1/7 + x) of the office

Also, that is 1/3 of the office, right? because they will finish in 3 hours. So in 1 hour, they finish 1/3 of the office

Now, you have 1/7 + x = 1/3

Solve for x is your turn.