Answer
$18$
Work Step by Step
$ \binom {3}{1}\binom {4}{2}=\dfrac {3!}{1!\left( 3-1\right) !}\times \dfrac {4!}{2!\left( 4-2\right) !}=\dfrac {3!}{1\times 2!}\times \dfrac {4!}{2!\times 2!}=3\times \dfrac {2!\times 3\times 4}{2!\times 2!}=3\times \dfrac {12}{2}=18 $
