To find the daily price decrease of the jacket, you can divide the total decrease over the 5 days by the number of days.
The total decrease is $21.50, and the number of days is 5.
Daily decrease = Total decrease / Number of days
Daily decrease = $21.50 / 5 = $4.30
So, the price is changing by $4.30 per day.
The correct answer is d) $4.30.