Answer
$70$
Work Step by Step
If we want to choose $k$ elements out of $n$ disregarding the order, not allowing repetition, we can do this in $_{n}C_k=\frac{n!}{(n-k)!k!}$ ways.
Thus here because the order doesn't matter, using a calculator $_{8}C_{4}=\frac{8!}{(8-4)!4!}=70$