Answer
$56$
Work Step by Step
Use the formula $C(n,r)=\dfrac{n!}{r!(n-r)!}$ to obtain:
$C(8,5)=\dfrac{8!}{(5!(8-5)!)}\\\\$
$C(8,5)=\dfrac{8!}{5!(3!)}\\\\$
$C(8,5)=\dfrac{8 {\times} 7 {\times}6{\times} 5 {\times} 4 {\times} 3 {\times} 2 {\times} 1}{(5 {\times} 4{\times}3{\times}2 {\times} 1)(3{\times}2{\times}1)}$
Simplify to get
$C(8,5)=56$
There are $56$ possible combinations.