The two points share the same y coordinate, which means that the line is horizontal, and this in turn means that the slope is 0.
Since a line written in slope-intercept form is
![y=mx+q](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tp90r2yjvg1zm38jsnadfw0t0gyrl2ly0y.png)
In the case of m=0 the equation is
![y=q](https://img.qammunity.org/2020/formulas/mathematics/high-school/5cn5wykl9wywvtg2xef2vzi7ehe4vr1o4n.png)
where the constant
is the common y coordinate shared by all points.
So, in your case, the equation is
![y=4](https://img.qammunity.org/2020/formulas/mathematics/high-school/jszmtghs7756m7cy884501rsvdvozrx7z2.png)