Note that “rate of change of the function” is a trivial name for “derivative of the function”.
So we just need to find the derivative of the function.
A linear equation should be easily found by:
(y - (-5)) / (x - 0) = (-5 - 0)/(0 - 2.5)
2x - y - 5 = 0
y = 2x - 5
Taking the derivative with respect to x:
dy/dx = 2
Done.
By the way it’s equivalent to the slope of the function. ; )
