so you're going to need to find the slope. in order to do that use (y2-y1)/(x2-x1)
(7-(-2))/(0-8)
simplify
9/-8
simplify -9/8
now using y=mx+b, we need to find b. so we can plug in the coordinates of (0,7) or (8,-2). let's use (8,-2) because it involves more math.
y=mx+b
-2=(-9/8)(8)+b
multiply (-9/8) by 8 to get -9
-2=-9+b
add 9 to both sides
7=b
so our equation is now
y=-(9/8)x+7
Part A:5=2x^2-x^2+13
5=x^2+13
0=x^2+13-5
0=x^2+8
Part B:5=2x^3-x^3+13
5=x^3+13
0=x^3+13-5
0=x^3+8
