Answer:
$99
Step-by-step explanation:
First, it was on sale for 10% off. 10% = 0.1 = 1/10. 1/10 of 100 is 10, so we subtract 10 (because 10% off) to get $90. Then, the sales tax, which we add, is 10%. 1/10 of 90 is 9, so we add 9 to 90 to get our total to be $99
