Last week Fred had 7 dollars and Jason had 47 dollars. Fred washed cars over the weekend and now has 17 dollars. Jason delivered newspapers and now has 8 dollars. How much money did they earn by washing cars?
Fred had 7 dollars and Jason had 47 dollars. 

Fred washed cars over the weekend and now has 17 dollars. 

Jason delivered newspapers and now has 8 dollars. 

How much money did they earn by washing cars? 

To solve this problem, we need to find out how much money Fred earned by washing cars. We can do this by finding the difference in Fred's money before and after he washed cars. 

Before: 7 dollars 
After: 17 dollars 

The difference is 10 dollars. This means that Fred earned 10 dollars by washing cars.