Answer
$18$
Work Step by Step
We know that $C(n,r)=\dfrac{n!}{(n-r)!r!}$. and $C(n,0)=1$.
Hence,
$C(18,1)=\dfrac{18!}{(18-1)!\cdot1!}=\dfrac{18\cdot17!}{17!\cdot1}=18$
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