Answer: $4.28
Explanation:
To find the opposite of being short $4.28, we will find the opposite of -$4.28. Since the customer is short $4.28, this means they have negative $4.28 from what they need.
-$4.28 ➜ $4.28
The opposite of being short $4.28 (aka -$4.28) is +$4.28.