the slope of a point is [tex] \frac{y2-y1}{x2-x1} [/tex]
so
[tex] \frac{7-7}{7+3} [/tex]
[tex] \frac{0}{10} =0[/tex]
having the slope equal zero just means that there is no change in the y values
which means that they are on the same horizontal line which they are at y=7
