Slope-intercept form: y = mx + b
(m is the slope, b is the y-intercept or the y value when x = 0 --> (0, y) or the point where the line crosses through the y-axis)
For lines to be parallel, they need to have the same slope.
y = -x - 6 The slope is -1, so the parallel line's slope is also -1.
Now that you know the slope, substitute/plug it into the equation:
y = mx + b
y = -x + b To find b, plug in the point (-9, -4) into the equation, then isolate/get the variable "b" by itself
-4 = -(-9) + b (two negative signs cancel each other out and become positive)
-4 = 9 + b Subtract 9 on both sides to get "b" by itself
-4 - 9 = 9 - 9 + b
-13 = b
y = -x - 13
