Terry has a coupon for sunglasses at a store near his house. With the coupon, when you buy one pair of sunglasses, you get the second pair for 30% off. Terry wants to use this coupon to buy two pairs of sunglasses that are each $45. Sales tax is 8%. How much does Terry save by using this coupon instead of buying the sunglasses at full price at this store?

First, let's calculate the total cost of buying two pairs of sunglasses without the coupon.

Since each pair is $45, the cost of two pairs would be 2 * $45 = $90.

Now, let's calculate the sales tax on $90. Sales tax is 8%, so the tax would be 8% of $90, which is 0.08 * $90 = $7.20.

Therefore, without the coupon, Terry would pay $90 + $7.20 = $97.20 for two pairs of sunglasses.

Now, let's calculate how much Terry saves by using the coupon.

With the coupon, Terry gets the second pair for 30% off, which means he would pay the full price of $45 for the first pair and 70% of $45 for the second pair.

So, he would pay $45 + 0.70 * $45 = $45 + $31.50 = $76.50 for two pairs of sunglasses with the coupon.

Therefore, Terry saves $97.20 - $76.50 = $20.70 by using the coupon instead of buying the sunglasses at full price.