[tex] C^{k}_{n}_} = \frac{n!}{k!(n-k)!}\\ \\ C^{100}_{28}_}= \frac{28!}{100!(100-28)!} =\frac{28!}{100!(72!)} [/tex]
[tex]\frac{28!}{100!(72!)}= \frac{1\cdot2\cdot3\cdot4...\cdot28}{(1\cdot2\cdot3\cdot4...\cdot100)(1\cdot2\cdot3\cdot4...\cdot72)} =[/tex]
