You have the correct slope for the blue line (1/2) and the correct perpendicular slope (-2). Nice work.
The issue appears to be with the green line. I have a feeling it can be moved around, and your teacher wants you to draw it perpendicular to the given blue line.
The question is: what point should the perpendicular green line pass through? That isn't entirely clear so you'll need to ask your teacher for further clarification.