Sorry if this is a stupid question.
The formula for relativistic Velocity-addition is
$u = (v + u') / (1 + (vu'/c^2))$
It seems that v, v', u, and u' are vectors, while c is a scalar.
But 1 seems to also be a scalar?
$(vu'/c^2)$ results in a vector.
You can't add a scalar to a vector. $1 + (vu'/c^2)$
I can't seem to find any info about this specifically online.
What obvious thing am I missing here?