Answer:
z=-3
Step-by-step explanation:
May I suggest using mathaway or photomath. It would help you with problems like this
let's say the breakfast price was "x", so that's the 100%, and we know she gave 20% of that and that is 1.80.
so, 1.80 is 20%, and "x" is the 100%, what is "x"?

The answer is b because it goes up down then up