The rate of change is the same as the slope.
Let's find the slope of function 1 using the Rise Over Run rule.
The rise is 2 and run is 1. So your rate of change is 2/1 or 2 for function 1
Function 2 is a y = mx + b equation, the slope is usually "m" or before the x
y = 1/2x + 7
1/2 is your rate of change for function 2