Answer
$70$.
Work Step by Step
The order matters here, so it is basically $C(8,4).$
We know that $C(n,r)=\frac{n(n-1)(n-2)...(n-k+1)}{r!}$. Also $C(n,0)=1$ by convention. Also $C(n,r)=C(n,n-r).$
Hence $C(8,4)=\frac{8\cdot7\cdot6\cdot5}{4!}=70$.