a) Use rise over run,
() count how far apart up/down the y's are, and how far apart left/right the x's are
() down in the y's mean it is negative
b) change in y over change in x
() y2 - y1 / x2 - x1
c) find the "m" when it is in slope-intercept form
() y = mx + b
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather