B) The equation you found (y=4x-5) is a graph of a line. This means the footprint path is in a straight line, and all other points can be found using that equation.
C) Pick any value of x. Plug it into your equation and solve for y.
Example: x = 258
y = 4(1032) - 5
y = 4128 - 5
y = 4123
They would find another one at (258, 4123)
You can do this for any value of x.
