First team can be selected in $\left( \, ^{15} C_{1} . ^{15} C_{1}\right)$ way second in $\left(^{14} C_{1}\right)\left(^{14} C_{1}\right)$ way's and so on
So number of ways of selections $15$ teams $=\frac{\left(15 !\right)^{2}}{15 !}=\left(15 !\right)$