First, let's find the total miles traveled between fillings:
[tex]28,176-27,892.5=283.5[/tex]we have that the distrance traveled was 283.5 miles. Now we can divide this number by the 17.5 gallons to get the following:
[tex]\frac{283.5}{17.5}=16.2[/tex]therefore, the driver got 16.2 miles per gallon