Find the slope and y-intercept.
x = –7
is it:
(A) Slope: undefined; y-intercept: (0, –7)
(B) Slope: 0; y-intercept: none
(C) Slope: undefined; y-intercept: none
(D) Slope: 0; y-intercept: (0, –7)

Draw the graph:  Think of it as 

x + 0y = -7

Find some points.  

Arbitrarily substitute 3 for y

x + 0(3) = -7

       x = -7

So one point on the line is (-7, 3)

Arbitrarily substitute -4 for y

x + 0(-4) = -7

        x = -7

So another point on the line is (-7, -4)

Plot those two points and draw a line through them:



As you can see it doesn't have a y-intercept because
it is parallel to the y-axis and doesn't intercept it
at all.  

It does have an x-intercept at (-7,0)

If we try to find its slope with the slope formula

     y2 - y1
m = —————————
     x2 - x1

using the two points we found (-7, 3), (-7, -4)

where (x1, y1) = (-7, 3) and (x2, y2) = (-7, -4), we get

     (-4) - (3)     -4 - 3     -7
m = ———————————— = ———————— = ———— 
    (-7) - (-7)     -7 + 7      0 

Division by 0 is undefined so the
slope is undefined.

The correct choice is 

(C) Slope: undefined; y-intercept: none

Edwin