Answer: Let's first figure out how many wallet-size photos we can buy with the remaining money after buying one large photo.
We have $20 to spend, and we spend $9.66 on the large photo, which leaves us with:
$20 - $9.66 = $10.34
We can divide this amount by the cost of each wallet-size photo to get the maximum number we can buy:
$10.34 / $0.55 = 18.80
Since we cannot buy a fraction of a photo, the maximum number of wallet-size photos we can buy is 18.
Therefore, we can order one large photo for $9.66 and 18 wallet-size photos for $9.90 ($0.55 x 18), which adds up to $19.56. This leaves us with $0.44 unspent.
Step-by-step explanation: