Chapter 2 - Section 2.3 - Writing Equations of Lines - 2.3 Exercises - Page 173: 61

$y-5=0$

Using $y-y_1=m(x-x_1)$ or the point-slope form of linear equations, the equation of the line passing through $( 9,5 )$ and with a slope of $m= 0 $ is \begin{array}{l}\require{cancel} y-5=0(x-9) \\\\ y-5=0 .\end{array}