I have an exam in a few hours and I would like someone to solve 2 questions and tell me each step they did along the way, 1 question i ahve done and the other is similar but i can seem to get the correct answer:

Q1: L=(0,-1,0) M=6,5,3) P=(3,0,1)

P is not on the line LM, find a point on line LM, called N, which is perpendicular to P.

This one i can do and I get N=(2,1,1)

Q2: x=2t y=-t z=4t.

Find a point Q on this line closest to a point P, not on this line.

I get the wrong answer for this 1, I think its because i am finding line PQ instead of QP. Is this where i am going wrong?, also if it is can someone tell me why it matters that QP is used and not PQ?