Answer:
x = 3
Step-by-step explanation:
y = 3 is the equation of a horizontal line parallel to the x- axis.
A line perpendicular to it must 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 (3, 5) with x- coordinate 3 , thus
x = 3 ← equation of perpendicular line