Last week Fred had 32 dollars and Jason had 15 dollars. They washed cars over the weekend and now Fred has 1 dollars and Jason has 27 dollars. How much money did Jason make over the weekend?
Fred had 32 dollars and Jason had 15 dollars. 

This means that, in total, there was 47 dollars. 

After they washed cars over the weekend, Fred had 1 dollar and Jason had 27 dollars. 

This means that, in total, there was 28 dollars. 

So, Jason made 27 - 15 = 12 dollars over the weekend.