Function 1 is the graph of a horizontal line. And the rate of change of a horizontal line is always 0 because there's is no change of y's.
So, rate of change of function 1= 0.
Slope intercept form of a line is y=mx+b where m= rate of change and b= -intercept.
By comparing the given function 2: y= 8x+12 with y=mx+b we will get m= 8.
So, rate of change of function 2= 8
Difference of rate of change of function 2 with 1 = 8-0= 8
So, the rate of change of function 2 is 8 more than the rate of change of function 1.
