Answer:
D m = 18g, where g is the number of gallons of gas.
Explanation:
Since he can go 18 miles per each gallon of gas, that means for gallon he can go 18 miles.
18g is just like 18 times the number of the gallons of gas.
So if I were to have 2 gallons of gas, I would plug in 18(2) so I would go 36 miles.
Hope this helps! ;)