3x + 5y ≥ -15 (1)
3x - y > 3 (2)
From (1) let's solve for x:
3x + 5y ≥ -15
Subtract 5y from both sides:
3x ≥ -15 - 5y
Divide both sides by 3:
x ≥ -5 - 5y/3 (3)
Replace (3) into (2)
3(-5 - 5y/3) - y > 3
Using distributive property:
-15 - 5y - y > 3
-15 - 6y > 3
Solving for x:
Add 15 to both sides:
-6y > 18
Divide both sides by -6:
y < -3
Replacing y into (3)
x ≥ 0
3x - y > 3
if x = 4 and y =9
3*4 - 9 >3
12 - 9 > 3
3 > 3
this is false because 3 = 3
