Answer:
x = 4
Step-by-step explanation:
y = - 3 is the equation of a horizontal line parallel to the x- axis.
A line perpendicular to it will therefore be a vertical line parallel to the y- axis with equation
x = c
where c is the value of the x- coordinates the line passes through.
The line passes through (4, - 6) with x- coordinate 4, thus
x = 4 ← equation of perpendicular line