I'm coming up with a very large answer. Not sure what I am doing incorrect.

Question

Find the indicated expression, where n = 7, r = 5. (Simplify the answer as much as possible.)

Answer 1

Substitute your numbers first to get (7!) / ((7-5)!(5!))

(7-5)=2 so you have (2!)(5!) in the denominator...

Now write out what the factorial really means... and simplify before you multiply anything.

7*6*5*4*3*2

(2)(5*4*3*2)

Simplify... you can initially get rid of all but....

7*6

2

and that simplifies to 7*3 which is 21.

That's your answer!