Alright this seems a pretty easy vector question, just wondering if it's me or the solutions I've got that are wrong.

First I found the line PQ, this is equal toIf P and Q are the points with position vectorsp = −i+3j+2kandq = i−7j+4krespectively, find the position vector of the mid-point of the line PQ.q-pwhich can easily be calculated to be2x-10y+2z. The midpoint is just half of this which isx-5y+z.

In the solutions however they have usedp+qto calculate the line PQ, is there something obvious I'm missing?

Thanks in advance to the person who sorts this annoying little problem out for me