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?
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?

We can set up an equation to solve this problem:

y = x - w

y - x = w

y - w = x