y = mx + b
To find the slope(m), you use the slope formula:
You plug in the points into the equation.
The slope is 0
y = 0x + b
Any number multiplied by 0 is 0. So:
y = b
To find b, you plug in the y value of either of the points.
-4 = b
Your equation is:
y = -4 (This is a horizontal line)
