Perpendicular (opposite slope)
only you have to do it flip the original slop and change the sign
original slop is -3x (filp it)

and change the sign (negative) become (positive)

is the perpendicular slop of the original line
remember
opposite slop (perpendicular line)
Same slop (parallel line )
y intercept is doesn't matter will be same or will be different
hope it will help you