Answer:
$34.40
Explanation:
this equation has 3 steps
1. to find out how much the dvds cost without any discount or tax: $40
2. the price of the dvds with the 20% discount, which can be found with cross-multiplication making the price after discount $32
3. the final price of the dvds with sales tax can be found also with cross-multiplication and the final answer would be 34.4