Answer:
$19.79
Explanation:
The only problem provided is #8, so I will help on that one lolz.
First, you find 10% of $19.99.
That is $2
This is a discount, so subtract 2 from the original, 19.99.
You get 17.99.
Adding a sales tax of 10% is $1.80.
This makes $19.79