write the equation for each of these segments.

(5,7) (7,4) Y = mx + b
7 = -3/2(5) + b
7 = -1.5 + b
b = 8.5
Y = -3/2(5) + 8.5
Y = -15/2 + 8.5
-15/2 + 8.5/1
-15/2 + 17/2
2/2 = 1

(-5,4)(-5,7) Y = mx + b ***Don't know how to
solve this one
since it is undefined
4 = 3/0(-5) + b
4 = -15 -4
Y = 19

slope = -3/2

use the point-slope form, then change to slope-intercept:
y-7 = -3/2 (x-5)
y = -3/2 x + 29/2

The line is vertical, since both points have the same x-coordinate. So,

x = -5

Always check for horizontal/vertical lines first.