qwertyboss:

you are not wrong, but the approach for secondary school lads is the way the op solved it

The "secondary school approach" is not legitimate as it doesn't agree with the concept of vectors and it's algebraic operations.

Martinez39:
He didn't solve it and his answer was plain wrong. His approach was wrong and it defied the understanding of vectors. His answer being slightly different was just a coincidence.

quite indirectly,I did point out that his elementary approach to the question was what accounted for his answer being correct,although I know that their were fluctuations in his approach .
for instance he neglected the use of component equality that satisfies the scalar m,to find the answer,

besides I don't think his audience needed such a breakdown of the vector concept