The equation of a parallel line will have the same x-term, but a different constant (y-intercept). The required value can be found by putting the given point values in to the equation to see what it needs to be.
Two angles are said to be supplementary if they add up to 180 degrees. So the supplement of an angle is obtained by subtracting it from 180. i.e., if x is an angle, its supplement is 180−x