Paul got a box of w erasers and x crayons for his birthday. At the end of the school year he only had y crayons left while not having lost a single eraser. How many more crayons than erasers did he have left?
e know that at the end of the school year, Paul had y crayons left and no erasers left. This means that at some point during the school year, he must have used up all of his erasers. 

We also know that he started with w erasers and x crayons. This means that at some point during the school year, he must have had w erasers and x crayons. 

Now, we can set up the equation w + x = y. This equation says that the total number of erasers and crayons he started with is equal to the total number of crayons he had at the end of the year. 

From here, we can solve for x. We know that w + x = y and w = 0. This means that x = y. Therefore, Paul had y more crayons than erasers at the end of the year.