Last week Fred had 26 dollars and Jason had 42 dollars. Fred washed cars over the weekend and now has 47 dollars. Jason delivered newspapers and now has 24 dollars. How much money did they earn by washing cars?
Fred had 26 dollars and Jason had 42 dollars. 

Fred washed cars over the weekend and now has 47 dollars. 

Jason delivered newspapers and now has 24 dollars.

This means that Fred earned 21 dollars from washing cars, and Jason lost 18 dollars from delivering newspapers.