Sammie paid $15.16 less than the original price which is 40% of the original price. that means she got a 40% discount.
work:
37.90/2 is 50% of the price
$18.95 = 50%
divide that by 5 you get 10% of the price
$3.79 = 10%
multiply by 4 you'll get 40% of the price
$15.16 = 40%
