Based on the discount rate and the sales tax, the original price of the computer was $750.
First find the price before tax. This can be found as:
= Computer price / (1 + tax)
= 688.50 / (1 + 8%)
= $637.50
Then find the price without the discount as:
= Price without tax / (1 - discount rate)
= 637.50 / (1 - 15%)
= $750
Find out more on discounts at https://brainly.com/question/1548141.