Answer:
$40.8
Step-by-step explanation: a $16 book at 15% off is $13.6. You can find this by first finding the amount deducted from the price (16 x 0.15 = $2.4) then subtract that amount from the original price ($16 - $2.4 = $13.6). Since it asks how much three books are, all you have to do is multiply the price of the discounted book by 3 ($13.60 x 3 = $40.80)