Slope is rise over run, change in y over change in x. Here we have points (1,3) and (3,9)
[tex]\textrm{slope} = \dfrac{\textrm{change in y}}{\textrm{change in x}} = \dfrac{9-3}{3-1} = \dfrac{6}{2} = 3[/tex]
Answer: 3
That's checked by verifying the line goes up 3 for one to the right. It does.