Aha! I love these types of questions. This is where you are going to use point-slope form!
As a reminder...point slope form is [tex]y - y^1 = m(x-x^1) [/tex]
So if we have our coordinates (4, -7) -- 4 would be [tex]x^1[/tex] and -7 would be [tex]y^1[/tex] -- now you need to plug them in.
But remember m = slope.
y + 7 = 3 (x - 4) -- now convert into standard form.
Standard form: y = 3x - 19