Not addition, since

and 0 doesn't belong to the set.
Not subtraction, since

.
It is closed under multiplication. The set appears to contain all non-zero multiples of 3.
Not division, since dividing some of the numbers results in rationals which do not belong to the set.
What other operations are you supposed to consider?
Answer:

So if they meant
then the answer is:
.
The choice this corresponds to is A.
Step-by-step explanation:
The sum of cubes formula for factoring or expanding:

You have I'm assuming they meant:
.
Compare
to
.
You should see in place of
you have
.
You should also see in place of
you have
.





Let's check it for fun.
So we are going to use the distributive property.
We are going to distribute all the terms in the first ( ) to all the terms in the second ( ).
+ 
+ 
Combine like terms:

Simplify the grouping of like terms:

0 times anything is 0:

The answer would be 2.6353, hope this helps. ^^
Fifteen thousand , four hundred and nine