Aos= -b/2a so plunin your numbers and you'll get the AOS so you can find the vertex
7. D
8. D
9. D
10.C
for 7 & 8 you use the equation

your points are (3,8) & (9,5)
so you plug the numbers in
y2= 5
y1=8
x2=9
x1=3
you subtract them get a fraction and that is your slope
9 & 10
use the equation

plug you numbers in for y1 and x2 m is your slope plug it in and that is your equation
Yes this is correct because that angle in is with the other angles to
Points on BC:
(-5, 5) and (0,1)
Slope = (5-1)/(-5-0)
Slope = -4/5
y = mx + c
y = -4/5x + c
at point (0,1)
1 = -4/5(0) + c
c = 1
y = -4/5x + 1
5y = -4x + 5
4x + 5y = 5 (Answer D)