Here's what I did which might help you
Answer:

Step-by-step explanation:
The question is

collect like terms

Answer:
y = -1/2x + 4
Step-by-step explanation:
You can see that the slope is -1/2 because of the rise over run.
It also crosses the y axis at 4,
so it is y = -1/2x + 4
I am not going to give you the answer, but I am going to tell you how to do it. You first put 18 over 1, and multiply that by one half. (You multiply across.)