Answer:
5x+2x
(5x+2x)
7x
3x+5 + 4x-1
add 3x and 4x
7x+5-1
7x+4
x²+12x-8 + 3x²-10x-2
-2x²+12-8-10x-2
-2x²+2x-10
-2 x² -x+5
