Can you solve (5,8,12) = s(1,1,1)+t(1,2,3) for s and t? In other words does point (5,8,12) lie on the plane through the origin that is spanned by the vectors (1,1,1) and (1,2,3).

I'm new with vectors and not really sure where to start. I don't understand the question, how do 2 vectors compose a plane?