For this case we have that by definition, the equation of a line in the slope-intersection form is given by:

Where:
m: It's the slope
b: It is the cut-off point with the y axis
On the other hand we have that if two lines are perpendicular, then the product of their slopes is -1. So:

The given line is:

So we have:

We find 

So, a line perpendicular to the one given is of the form:

We substitute the given point to find "b":

Finally we have:

In point-slope form we have:

ANswer:

72 miles=1 gallon
Step by step Explanation:
Divide 1080 by 15 and divide 15 by 15. You get 72 and one.
Hope me helped!