Substitution need some variable by itself
3x + 4y = -5
3x = -4y - 5
x = -4/3y - 5/3
Now plug this into second equation
2(-4/3y-5/3) - 3y = 8
(-8/3y - 10/3 - 3y = 8) * 3 (rid of fraction)
-8y - 10 - 9y = 24
-17y - 10 = 24, -17y = 34, y = -2
Now plug into any equation
3x + 4(-2) = -5
3x - 8 = -5
3x = 3, x = 1
Solution: x = 1, y = -2