So, let's try applying the discount before the sales tax first. Because it's a 15% discount, the earrings will be 85% of their original cost. (100 - 15 = 85). You can turn this percentage into a decimal (0.85) and multiply.
0.85 * 10 = 8.5.
Because we're working with money, this becomes $8.50. But we still need to add the sales tax. 8% can also be expressed as 0.08.
0.08 * 8.50 = 0.68.
So we add the sales tax, $0.68 to the discounted price of the earrings, $8.50.
$8.50 + $0.68 = $9.18.
Now let's try applying the sales tax first. 0.08 * 10 = 0.8
10 + 0.8 = 10.8. But again, we're working with money so this becomes $10.80.
Now we apply the discount. 0.85 * 10.80 = 9.18.
So whether you apply sales tax before the discount, or the discount before the sales tax, the cost of the earrings comes out to $9.18. It doesn't matter.
