Last week Fred had 7 dollars and Jason had 14 dollars. They washed cars over the weekend and now Fred has 11 dollars and Jason has 28 dollars. How much money did Jason make over the weekend?
Fred had 7 dollars and Jason had 14 dollars. 

This means that Jason had 7 more dollars than Fred. 

After they washed cars over the weekend, Fred had 11 dollars and Jason had 28 dollars. 

This means that Jason had 17 more dollars than Fred. 

Therefore, Jason made 10 dollars over the weekend.