Answer:
r = 3.
Step-by-step explanation:
Equation of a line:
The equation of a line has the following format:
[tex]y = mx + b[/tex]
In which m is the slope.
Finding the slope of a line, given two points:
When we are given two points of a line, the slope of the line is given by the change in y divided by the change in x.
Points (4,r), (r,3)
Change in y: 3 - r
Change in x: r - 4
Slope is 0, so:
[tex]\frac{3 - r}{r - 4} = 0[/tex]
[tex]3 - r = 0[/tex]
[tex]r = 3[/tex]
The value is r = 3.