To find the daily price change, you divide the total decrease in price by the number of days.
The total decrease is $21.50 over 5 days.
So, the daily price change is:
\[ \text{Daily Change} = \frac{-21.50}{5} = -4.30 \]
Therefore, the price is changing by \(-4.30\) dollars per day.
The correct response is:
−$4.30.