Final answer:
Harper will pay $87 for a case of 48 glasses that retails for $145, using the complement method to calculate the trade-discount rate.
Step-by-step explanation:
To determine how much Harper pays for a case of 48 glasses, we need to calculate the trade-discount rate. The trade-discount rate is granted by National Stemware and Accessories and is 40%. To find the amount Harper pays, we can use the complement method. The complement of 40% is 100% - 40% = 60%.
Since the retail price of the case of glasses is $145, Harper will pay 60% of $145. To calculate this, we multiply $145 by 0.6: $145 * 0.6 = $87.
Therefore, Harper will pay $87 for a case of 48 glasses that retails for $145. So the correct answer is C) $87.