I thought A and B are just two points. So, the line between them is B-A (8-1, 12+2,-3-4) You get (7,14,-7) Than you divide this by seven because there are seven parts total (ratio 2:5). You get (1,2,-1) --- This is for one part. So the answer is (1, -2, 4) + 2(1,2,-1) = (3,2,2)
I am not sure...