As far as i can see it looks good.
So for a you used f(b)-f(a)/b-a , for b you found f'(3) and your line equations look good.
a. Find the average rate of change of over the interval
b. Find the rate of change of at
c. Find the equation of the tangent line at
d. Find the equation of the normal line at
Here are my answers, are they correct?