The first step is to recognize that the equation describes a vertical line in problem 3 and a horizontal line in problem 5. The perpendicular to a vertical line is a horizontal line, and vice versa.
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3. To make the desired horizontal line go through the point (-8, -1) the y-value of the line must match that of the point:
y = -1
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5. To make the desired vertical line go through the point (-14, 81), the x-value of the line must match that of the point:
