please

18!/4!(18-4)!=

\(\begin{array}{|rcll|} \hline && \frac{18!}{4!(18-4)!} \\ &=& \binom{18}{4} \\ &=& \frac{18}{4}\cdot \frac{17}{3}\cdot \frac{16}{2}\cdot \frac{15}{1} \\ &=& \frac{18}{2}\cdot \frac{17}{1}\cdot \frac{16}{4}\cdot \frac{15}{3} \\ &=& 9\cdot 17\cdot 4\cdot 5 \\ &=& \mathbf{3060} \\ \hline \end{array} \)

Im going to assume this problem is (18!)/((4!)(18-4)!)

=(18!)/((4!)(14)!)

=(18!)/((4!)(14!))

=(18*17*16*15*14!)/((4!)(14!)) by definition of factorial

=(18*17*16*15)/((4!))

=(18*17*16*15)/((4*3*2*1))

=(9*17*4*5)/1

=9*17*4*5

=20*9*17

=3060