Don't need an explanation! just correct answers ! i'm so stressed : /

Y=mx you just multiply m and x :)
3
0
-3
-6

We know, the principle equation of line, 
y = mx + c
when, x = -1, y = 3, m = -3, c =?
3 = (-1)(-3) + c
c = 3 - 3 = 0

When, x = 0, y = (-3)(0) = 0
x = 1, y = (-3)(1) = -3
x = 2, y = (-3)(2) = -6 

In short, Your Answers would be 0, -3, -6

Hope this helps!

The slope best fit isc. 1/6 mile per hour