The question is vague.
I will assume you're asking What is the point-slope equation of a line which has a gradient of 0 and contains the point (3,1)?
Since the gradient is 0, the line is horizontal or of the form
[tex]y=c[/tex]
Since from the point we can recognize that the value of y is 1, the resulting equation is
[tex]y=1[/tex]
