Answer:
$4.20
Explanation:
What you bought will be subtracted from how much you paid with.
amount paid - amount bought
We paid for the cookie with $5, and bought something for 80 cents.
$5 is equal to 5.00, and 80 cents is equal to 0.8
5.00-0.8=4.2
So, you would get $4.20 back in change