-9x + 9y ≥ -81
9(-x+y) ≥ -81
-x + y ≥ -9
y ≥ x - 9
Graph the line y = x - 9. The line has a slope of 1 and a y-intercept of -9. Since the inequality is ≥, it includes the line, so draw the line as a solid line. To determine which side of the line satisfies the inequality, pick a point on one side of the line, plug in the values and see if the inequality is true. If it is, then that side of the line is the solution side. If not, the other side is the solution side. A good point to pick is (0,0):
y ≥ x - 9
0 ≥ 0 - 9
0 ≥ - 9
which is true. So the side of the line with the point (0,0) is the solution side. Shade it in.
