The unit rate means how much is one of the thing you are working with. In this case, the unit rate of a pint (16 ounces) is how much just one ounce will cost. So divide $3.93 by 16
$3.93/16 = $0.245625
Since we're working with money, round to the nearest hundredth
Unit rate is $0.25 per ounce, or 25 cents per ounce
