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