Answer
$56$
Work Step by Step
Using $\left( \array{n\\r} \right)=\dfrac{n!}{r!(n-r)!},$ the given expression, $\left( \array{
8\\5
} \right)$ evaluates to
\begin{array}{l}\require{cancel}
=\dfrac{8!}{5!(8-5)!}
\\\\=
\dfrac{8!}{5!3!}
\\\\=
\dfrac{8(7)(6)(5!)}{5!(3)(2)(1)}
\\\\=
\dfrac{8(7)(\cancel{6})(\cancel{5!})}{\cancel{5!}\cancel{(3)(2)}(1)}
\\\\=
\dfrac{56}{1}
\\\\=
56
\end{array}
