First realize that the line is a vertical line with an undefined slope and that a line perpendicular to a vertical line must be a horizontal line with a zero slope having an equation
In this case, you want to be equal to the y-coordinate of the given point so that you have a line perpendicular to the given line through the given point.
The original equation and the just-derived equation for the perpendicular form a system of equations. Solve this system for the point of intersection of the the two lines using any appropriate method. Substitution is likely to be the best method here.
Determine the distance between the given point and the just-derived point of intersection using the Distance Formula:
The result of this final calculation is the answer to the problem.
