Answer:
a) 7z³+2z²-2z+1
b)2x²+3x-8
Step-by-step explanation:
a) (7z³+4z-1)+(2z²-6z+2)
7z³+2z²-2z+1
b) (5x²-2x-1)-(3x²-5x+7)
5x²-2x-1-3x²+5x-7
2x²+3x-8
That is not correct. I will help you. Begin by subtracting the 9x from both sides, like this: 9x - 9x + 2y = 6 - 9x. That simplifies to 2y = -9x + 6. Now divide both sides by 2 to get y all alone, like this:

. That reduces down to

. That is slope-intercept form. y = mx + b.
15?im not sure...but I think thats right
The cordoned are 7.8 and 466.0006