Chapter 2 - Section 2.3 - Writing Equations of Lines - 2.3 Exercises - Page 173: 55

$x=7$

The given points, $( 7,6 )$ and $( 7,-8 )$ form a vertical line. Since the equation of vertical lines takes the form $x=a$ where $a$ is the $x-$intercept, then the equation of the line is \begin{array}{l}\require{cancel} x=7 .\end{array}