Answer:
horizontal
Explanation:
You want to know if the equation -4y = 72 describes a horizontal or vertical line.
Constant equation
The equation reduces to ...
-4y = 72
y = -18 . . . . . . . . divide both sides by -4
The points on a graph that have y-coordinate -18 will form a horizontal line. They are all 18 units below the x-axis. The line is parallel to the x-axis.
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Additional comment
The equation x = constant describes a vertical line.
If you are in doubt, you can always graph the equation with your graphing calculator.