Mrs. davis bought 6 pounds of grapes for $18 at this rate how much would 72 ounces of grapes have cost

If you would like to know how much would 72 ounces of grapes have cost, you can calculate this using the following steps:

6 pounds of grapes ... $18
72 ounces of grapes = 4.5 pounds of grapes ... $x = ? 
72 ounces = 4.5 pounds

6 * x = 18 * 4.5
x = 18 * 4.5 / 6
x = $13.5

The correct result would be $13.5.