1a (4x-3y)+(4x+3y)=8x
1b (3+2x-x²)+(x²-x)=3+2x-x²+x²-x=3+x
2a (5x-y)-(5x+y)=5x-y-5x-y=-2y
2b (4-x+3x²)-(2x²-x+4)=4-x+3x²-2x²+x-4=x²
3a 6y²+3-2y+2y²=8y²-2y+3
3b 9+y²-4+5y=y²+5y+5
3c 2y-5+3y²+4-y²=2y²+2y-1
3d 6-9+2y²+6y²-7y+3+7y=8y²
4a 2x²+(2x-4)
4b 4x-(2x-1)
5a 9-x+(-2y+3z)
5b 9-x-(2y-3z)