Answer:
Option D
Explanation:
Given that John drives 257 miles and uses 9 gallons of gas.
we can find unit rate as
Per galon mileage given = 257/9 = 28
ANd units are miles/gallon
100 miles per gallon is very far from 28 hence incorrect
6 miles per gallon is very low
30 is right but unit is wrong
Hence option D is the right answer.