Answer:
a girl was mean so I had to beat her up
Step-by-step explanation:
that is when I had met a mean person
Remark
Many calculators have a key that will do this in one step. Mine is one of them. So let's start with the answer and then we'll do it the long way.
9C3 = 84. You put it into your calculator as 9 2nF nCr 3 =
Solution

3*4*7 = 84 which is what you set out to show.