3x^2-5x+5x^2-3x
=(3+5)x^2+(-5-3)x
=8x^2-8x
5n+11=7n-9
-2n=-20
n=10
4(3x-5)=-2(-x+8)-6x
12x-20=2x-16-6x
12x-20=-4x-16
16x=4
x=1/4