Answer:
B. 3x^2 - 13x + 7
Step-by-step explanation:
6x^2 - 5x + 3 - (3x^2 + 8x - 4)
6x^2 - 5x + 3 - 3x^2 - 8x + 4
3x^2 - 13x + 7
x =-4
4x+9 = -2x-15
Add 2x to each side
4x+2x +9 = -2x+2x-15
6x+9 = -15
Subtract 9 from each side
6x +9-9=-15-9
6x = -24
Divide each side by 6
6x/6 = -24/6
x = -4
3