I have a homework problem that I am unable to get a clear explanation or walkthrough with and I do not understand how to get the final answer. I have been trying for over 2 hours now. The problem is:

Alright, so this is maybe where I keep getting it wrong. I think I do the Rules correctly and I see how you got dy/dx but when I plug in the coordinates to the equation to find the slope, the problem is incorrect after I use the formula: y - y1 = m(x-x1)