To compare the unit rates, we need to find the cost per ounce for each bottle of water.
For the 16-ounce bottle, the unit rate is:
$2.40 / 16 ounces = $0.15 per ounce
For the 28-ounce bottle, the unit rate is:
$2.80 / 28 ounces = $0.10 per ounce
From the unit rate we can see that the 28 ounce bottle of water is a better deal because it cost $0.10 per ounce while the 16 ounce bottle cost $0.15 per ounce.
It's important to know that as the amount of water increases the price decreases making the 28 ounce bottle cheaper than the 16 ounce bottle.