Find out the slope of the line
Looking a the graph
we have a proportional relationship between the variable d and variable g (because the line passes through the origin)
That means
The equation is of the form
d=Kg
where
K is the constant of proportionality or slope
K=d/g
we need one point to calculate the value of k
we take the point (6,150) from the graph
so
K=150/6
K=25 miles per gallon
