Hi guys, i have a question which seemed simple when i first read it but now i see for some reason i can't figure it out...

i have three 3D points: A(5,1,3) B(7,9,-1) and C(1,-15,11)

How can i determine if they are in a straight line?

I think it has something to do with finding the distances between the points but after that I dont know what i'm doing. Any help would be appreciated. thank you!