Answer
Rise/run = 20 miles/gallon
The equation of the line is y = 20x
Check Explanation for more.
Step-by-step explanation
The rise-run is another name for the slope.
For a straight line, the slope of the line can be obtained when the coordinates of two points on the line are known. If the coordinates are (x₁, y₁) and (x₂, y₂), the slope is given as

For this question,
(x₁, y₁) and (x₂, y₂) are (3, 60) and (4, 80)
x₁ = 3
y₁ = 60
x₂ = 4
y₂ = 80

The equation of the line is y = 20x
Hope this Helps!!!