since you're given with the coordinates of the point and slope then all you have to do is substitute:
[tex]y - y_1 = m(x - x_1)[/tex]
[tex]y - 2 = -3(x - 1)[/tex]
[tex]y - 2 = -3x + 3[/tex]
[tex]y = -3x + 3 + 2[/tex]
[tex]y = -3x + 5[/tex]
or you can have it as
[tex]y + 3x = 5[/tex]
