Ah- I'm not entirely sure what you mean but.
To find the slope (which I think that's what you mean) you do...
difference in y/ difference in x
3 - (-1) / 7 - 1
= 3 + 1 / 6
= 4/6
= 2/3
So k, or the slope would be 2/3
(Or if you're asking for an equation... use 3 - (-1) / 7 - 1)
(I'm so sorry for not being super helpful to you!)