Answer :
x ≥ -3
y ≥ 5x - 9
3x + y ≤ 15
3(-3) + (5x - 9) ≤ 15
-9 + (5x - 9) ≤ 15
(-9 - 9) + 5x ≤ 15
-18 + 5x ≤ 15
+ 18 + 18
5x ≤ 33
5 5
x ≤ 6.6
y ≤ 5(6.6) - 9
y ≤ 33 - 9
y ≤ 24
(x, y) ≤ (6.6, 24)
y ≥ 5x - 9
3x + y ≤ 15
3(-3) + (5x - 9) ≤ 15
-9 + (5x - 9) ≤ 15
(-9 - 9) + 5x ≤ 15
-18 + 5x ≤ 15
+ 18 + 18
5x ≤ 33
5 5
x ≤ 6.6
y ≤ 5(6.6) - 9
y ≤ 33 - 9
y ≤ 24
(x, y) ≤ (6.6, 24)