Answer:

Step-by-step explanation:
we know that
<u><em>Combinations</em></u> are a way to calculate the total outcomes of an event where order of the outcomes does not matter.
To calculate combinations, we will use the formula

where
n represents the total number of items
r represents the number of items being chosen at a time.
In this problem

substitute

simplify




Answer:
Step-by-step explanation:
C and D answers look good
C
I think this is the right answer
Answer- 21
-6+-9
—
-3
-6+27=21