Answer
$55$
Work Step by Step
The number of combinations of 11 items taken 9 at a time :
$C(11,9)=\frac{11!}{9!(11-9)!}=\frac{11!}{9!*2!}=\frac{11*10*9*8*7*6*5*4*3*2*1}{9*8*7*6*5*4*3*2*1*2*1}=\frac{11*10}{2}=5*11=55$
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