Use the slope formula.
[tex] \frac{y2 - y1}{x2 - x1} [/tex]
[tex] \frac{4 - 4}{7 - - 9} [/tex]
[tex] \frac{0}{16} [/tex]
The zero shows that this line has no slope.
(The slope is 0.)
Since it's on top, it tells you that this is a horizontal line.
If the 0 was on bottom, it would be a vertical line.
Hope this helped!
:)
