Last week Fred had 16 dollars and Jason had 39 dollars. Fred washed cars over the weekend and now has 24 dollars. Jason delivered newspapers and now has 17 dollars. How much money did they earn by washing cars?
1. Fred had 16 dollars and Jason had 39 dollars. 
2. Fred washed cars over the weekend and now has 24 dollars. 
3. Jason delivered newspapers and now has 17 dollars.

We want to know how much money Fred earned by washing cars. 

Step 1: We are given that Fred had 16 dollars and Jason had 39 dollars. 
Step 2: We are told that Fred washed cars over the weekend and now has 24 dollars. 
Step 3: We are told that Jason delivered newspapers and now has 17 dollars. 

From Step 2, we can see that Fred earned 8 dollars from washing cars.