The pre tax cost of the four DVDs will be:
4 × 9.99 = 39.96
6.75% tax will amount to 6.75/100 × 39.96 →.0675 × 39.96 = 2.697 or 2.70 rounded off.
Cost of DVDs after tax will be 39.96 + 3.70 = 42.66 $
20% discount will be 20/100 × 42.66 →0.2 × 42.66 = 8.53 $
Cost of DVDs with 20% discount will be 42.66 - 8.53 = 34.13
Rounded off to the nearest cent, the total cost of the order is 34 $ and 10 cents.
