2.39-0.15 = 2.24
2.24/64 = 0.035 per oz.
4 * 20 = 80 oz.
4 * .79 = 3.16
3.16 - 0.2 = 2.96
2.96/80 = 0.037 per oz.
A 64 oz. bottle of juice costs $2.39, and a 20 oz. bottle costs &0.79. You can use a 20-cents-off-coupon if you buy four 20 oz. bottles or a 15-cents-off-coupon if you buy a 64 oz. bottle. Which is the better buy?
2.24/64 = 0.035 per oz.
4 * 20 = 80 oz.
4 * .79 = 3.16
3.16 - 0.2 = 2.96
2.96/80 = 0.037 per oz.
For the 64 oz. bottle of juice that costs $2.39, the unit price is $2.39 / 64 oz. = $0.0373 per ounce.
For the 20 oz. bottle that costs $0.79, the unit price is $0.79 / 20 oz. = $0.0395 per ounce.
Now, let's consider the coupons.
For the 20 oz. bottles, you have a 20-cents-off coupon. So, the cost per bottle will be $0.79 - $0.20 = $0.59. The unit price will be $0.59 / 20 oz. = $0.0295 per ounce.
For the 64 oz. bottle, you have a 15-cents-off coupon. So, the cost for the bottle will be $2.39 - $0.15 = $2.24. The unit price will be $2.24 / 64 oz. = $0.035 per ounce.
Comparing the unit prices, the 20 oz. bottle with the coupon has the lower unit price of $0.0295 per ounce, which means it is the better buy compared to the 64 oz. bottle with the coupon that has a unit price of $0.035 per ounce.