Let's start by calculating the cost of the first 10 boxes, which totals $75, and the next 10 boxes cost $55.
Together, these 20 boxes amount to $130 spent. With $18 remaining, you can purchase 4 more boxes since 18 divided by 4.5 equals 4.
Therefore, the maximum number of boxes you can buy with $148 is 24.
The unidentified quantity is the framed prints (517)