The final discounted price of the hat can be calculated by subtracting the discount from the regular price, like this:
discounted price = regular price - discount
By calling x to the regular price, we can rewrite the equation to get:
discounted price = x - discount
The discount, is calculated by multiplying the regular price by the discount percentage, in this case, a 20% (0.2) discount is applied, then we can rewrite the above equation to get:
discount price = x - 0.2x
Then, option D x - 0.2x describes the discount price