If you purchased 18 units of iPhone cases, which is more than fifteen, you qualify for a 20% discount.
So, you paid 80% of the original price.
Let's call the original price X.
Then, you paid 0.8X for the 18 units.
We know that you paid $500, so we can set up the equation 0.8X = $500.
To solve for X, we divide both sides of the equation by 0.8: X = $500 / 0.8.
X = $625.
Therefore, the original price was $625.
#### 625
The answer is: 625
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
If you purchase more than fifteen units of iPhone cases, you can get a 20% discount. If you paid $500 for 18 units, what was the original price?

### Answer:
