[tex]\frac{14!}{12!2!}[/tex]
This is what it basically means:
[tex]=\frac{14*13*12*11*10*9*8*7*6*5*4*3*2*1}{12*11*10*9*8*7*6*5*4*3*2*1(2*1)} [/tex]
To simplify that, cross out numerators that are the same as the denominators because anything divided by itself equals 1.
[tex]=\frac{14(13)}{2*1}[/tex]
Now because anything multiplied by 1 stays the same, this simplifies to
[tex]=\frac{14(13)}{2}[/tex]
[tex]=\frac{182}{2}[/tex]
[tex]=91[/tex]
