Paco had w salty cookies and x sweet cookies. He ate y sweet cookies and z salty cookies. How many salty cookies did Paco have left?
Paco had w salty cookies and x sweet cookies. He ate y sweet cookies and z salty cookies. How many salty cookies did Paco have left?

Paco had w salty cookies and x sweet cookies. He ate y sweet cookies and z salty cookies. 

w - z = how many salty cookies did Paco have left