Answer :
9x - 5y > 20
9x - 9x - 5y > 20 - 9x
-5y > 20 - 9x
-5 -5
y > -4 + 9/5x
9x - 5(-4 + 9/5x) > 20
9x + 20 + 9x > 20
9x + 9x + 20 > 20
18x + 20 > 20
-20 -20
18x > 0
18 18
x > 0
9(0) - 5y > 20
0 - 5y > 20
+0 +0
-5y > 20
-5 -5
y > -4
(x, y) > (0, -4)
9x - 9x - 5y > 20 - 9x
-5y > 20 - 9x
-5 -5
y > -4 + 9/5x
9x - 5(-4 + 9/5x) > 20
9x + 20 + 9x > 20
9x + 9x + 20 > 20
18x + 20 > 20
-20 -20
18x > 0
18 18
x > 0
9(0) - 5y > 20
0 - 5y > 20
+0 +0
-5y > 20
-5 -5
y > -4
(x, y) > (0, -4)