Hi I really need help here.

I'm getting conflicting answers for both questions..

For the image with the P and Q complex number, to find the distance PQ, the textbook says to take z-w.

However, for the image of a parallelogram, to find PR, it is w-z.

I am really confused, If they ask to find eg. AB in terms of a and b, shouldn't B be the place where both arrowheads meet? And thus, A will be -A and thus, AB = b-a?!

Can someone explain what went wrong with my thinking process, I really am confused.

Thank you so much,

J.