We set up two points that lies on the line. We can observe that the points
(0, 0) and (2, 92) are part of the graphic.
We call (0, 0) our first point and (2, 92) our second point, then
(x₁, y₁) = (0, 0)
(x₂, y₂) = (2, 92)
We calculate the change of x and the change of y from the first point to the second point:
Δy = y₂ - y₁ = 92 - 0 = 92
Δy = 92 miles
Δx = x₂ - x₁ = 2 - 0 = 2
Δx = 2 hour
We calculate the unit rate dividing the change of variables:
Δy/Δx = 92/2 = 46
