In your given problems, you would use the given coordinate and plug in the x for xi and the y coordinate for yi. The y and x are left alone ( this is how you solve for y=mx+b).
Ex. #1: (2,2) m=-3
Equation: y-yi = m(x-xi) y-2 ( y coordinate) = -3(x-2)(the x coordinate). Simplify y-2 = -3x+6 —> y=-3x+8
