Velocity is a relative number. So let's say your are going 0.9 c but I'm going at 0.8 c now according to me you can go 0.7 more at least. But you're already goi

Velocity is a relative number. So let's say your are going 0.9 c but I'm going at 0.8 c now according to me you can go 0.7 more at least. But you're already going 0.9 and adding 0.7 will put you above speed of light. You can say you're already travelling faster than light relative to something out there... So what the hell are we talking about here?