The expression 0.08x+(x−200) models the final price of a computer with an instant rebate in a state that charges a sales tax.

enter the expression in the box that represents the amount of tax that is paid on the computer.
$

Final price of a computer: 0.08x + (x - 200)

x is the original price of the computer
200 is the instant rebate. 
x - 200 is the net cost of the computer.

0.08x is the amount of tax paid on the computer.

0.08 is the tax rate in decimal. It is 8% tax rate in percentage form.