Roy drives a sedan that gets mileage of 30 miles per gallon. If fuel consumption is represented by g and mileage by m, which function represents the relationship between m and g?
 m = f(g) = 30 × g
 m = f(m) = 30 × m
 g = f(m) = 30 + m
 m = f(g) = g − 30
 m = f(g) = g ÷ 30