Write an equation of a line perpendicular to line cd below in slope-intercept form that passes through the point (−1, 6).

line cd is shown. c is at 1, 1. d is at 3, 5.

y = −0.5x − 5.5
y = −0.5x + 5.5
y = 2x + 13
y = 2x − 13

First we have to calculate the slope of line CD

C(1,1) D(3,5)
m = (y2 - y1)/(x2 - x1) 
m = (5-1)/(3-1) = 2

We know that two lines are perpendicular if this happens 
m1*m2 = -1

so
2*m2 = -1
m2 = -1/2 = -0.5

and finally the equation for a line is: y - y0 = m( x - x0)
y = -0.5x - 5.5

Don’t know sorry about that