Can you please solve this I don't understand perpendicular lines

The equation of the perpendicular line 't' is  3x+y =0

Point slope form y = mx +C

                            y = - 3x

Step-by-step explanation:

Step(i):-

Given equation  s =    and given point (1,-3)

The equation of the perpendicular line

                 ⇒  3 y = x+30

               ⇒ x - 3y +30 =0

Step(ii):-

The perpendicular line of the given straight line 's'

       b x -ay +k=0

⇒  -3x -y +k=0

This line is passing through the point (1,-3)

     -3(1)-(-3)+k=0

            k =0

The equation of the perpendicular line   -3x-y =0

Final -

The equation of the perpendicular line   3x+y =0

Point slope form y = mx +C

                            y = - 3x

1/800 is the right answer