Question: Vector Question

I need to answer a question, using maple, mathcad, or a similar algebra solver.

I have a little experience in Maple, and thought it would be easy, buts its not, here is the question.

The question is

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Let P and Q be two points in the x-y plane with coordinates (1,2)  and (1,-1) respectively with respect to an origin O. Express OP, OQ and QP in the form Ai  + Bj   where A and B are scalars. Let R be a point on OP so that OR = 1/3OP . Find OR and QR in terms of i  and j .

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I have no idea how to do this.

This is how i was going to do it.

- Declare each letter using the vector values.

- Calculate combined values, using "Vector Add"

But then, I am not sure if i am going the right way?

It seems a new world, i am going throught the tutorial videos, managed to answer a few questions from them, but this one has me.

Any hints, or pointers in the right direction would be most appreciated, some samples would be even better, and even better still, samples with comments =)