The coordinate is given (-6,4) that passes through the equation of line and also a line which is perpendicular to the equation of line is y=-3.
The line that is perpendicular to y=−3 is a horizontal line, because horizontal and vertical lines (x- and y- axes for example) are perpendicular.
Therefore, this line will take the form x=n where n is the x-coordinate of the point passed through.
The x-coordinate of the given ordered pair (-6,4) is -6.
So the equation must be x=-6.