To find the unit rate of miles per gallon, you can divide the total number of miles Valerie can drive by the total number of gallons her car can hold.
Valerie can drive 288 miles on a full tank of gas, which holds 16 gallons.
To calculate the miles per gallon:
\[ \text{Miles per gallon} = \frac{\text{Total miles}}{\text{Total gallons}} = \frac{288 \text{ miles}}{16 \text{ gallons}} = 18 \text{ miles per gallon} \]
So, the unit rate is 18 miles per gallon.