Respuesta :

Answer:

21

Step-by-step explanation:

This is a combination of 7 objects taken 5 at a time

nCr = n! / r! * (n - r)!

7C5 = 7! / (5! (7-5)!)

       = 7! /(5! 2!)

       = (7*6*5*4*3*2*1)

          -----------------------

          5*4*3*2*1  * 2*1

Canceling

      =    7*6/ (2*1)

      = 21