25% off $100 = $75. You save $25.
Equation: $100 − (25% × $100) = $100 − $25 = $75.
Another way to read it: you pay 75% of the original price — that's $75.
$75. The discount is $25 and the final price you pay is $75.
You pay $75 (before tax). That's $100 minus a $25 discount.