Step 1: Understanding the Concept:
This is a reverse percentage problem. We are given the final price after a discount and need to find the original price.
Step 2: Key Formula or Approach:
If the sales price is the result of a discount, the relationship is:
\[
\text{Sales Price} = \text{Original Price} \times (1 - \text{Discount Rate})
\]
To find the original price, we rearrange the formula:
\[
\text{Original Price} = \frac{\text{Sales Price}}{1 - \text{Discount Rate}}
\]
Step 3: Detailed Explanation:
The sales price is $12,590.
The discount rate is 20% or 0.20.
This means the sales price represents \( 100% - 20% = 80% \) of the original price.
Using the formula:
\[
\text{Original Price} = \frac{\$12,590}{1 - 0.20} = \frac{\$12,590}{0.80}
\]
\[
\text{Original Price} = \$15,737.50
\]
Step 4: Final Answer:
The original price of the car was $15,737.50. The correct option is (D).