40% off $100 = $60. You save $40.
Equation: $100 − (40% × $100) = $100 − $40 = $60.
Another way to read it: you pay 60% of the original price — that's $60.
$60. The discount is $40 and the final price you pay is $60.
You pay $60 (before tax). That's $100 minus a $40 discount.