The answer is D
Hope this helps
Large would be 1495
Medium would be 997
Small would be 498
Look a the work I did, it has an equation in it. The equation I got is 3x+2x+x=2940
To find the volume of any cube you need to know the length, width and height. The formula to find the volume multiplies the length by the width by the height. The good news for a cube is that the measure of each of these dimensions is exactly the same. Therefore, you can multiply the length of any side three times, so 6 x 6 x 6 is just 216 in.
This arithmetic sequence has first term 6 and common difference -1. The general formula is
an = a1 +(n-1)d
For your sequence, this is
an = 6 +(n-1)*(-1)
an = 7 - n
We can easily enumerate E and F:
The intersection 
is a set composed by all the element belonging to both E and F, i.e. 4.
The intersection of this set with D works in the same way, but it's actually a trivial one, since is a subset of D. In fact, D is the set of all integers, while 4 is a particular integer. And in general, if A is a subset of B, then the intersection between A and B is A itself, so the final answer is
