Last week Fred had 36 dollars and Jason had 33 dollars. Over the weekend Fred delivered newspapers earning 13 dollars and washed cars earning 45 dollars. How much money did Fred earn over the weekend?
Fred had 36 dollars last week. 
He earned 13 dollars delivering newspapers. 
He earned 45 dollars washing cars. 

Adding those three numbers together, we get that Fred earned 94 dollars over the weekend.