Hey mate
It is C. 0 because there is no b in the <span>equation</span>
21.2264 is 21.2 rounded to the nearest tenths; the place after the decimal is there tenths place so in the hundreths place, the number 2 is less than 5 therefore rounding it to 2.
I'm presuming that the 'large cube' is made from 8 cubes the same size as the 8 cubes in the long row. They both have the same volume, the only difference between them is that they are arranged in a different order. Hope this helps. If not feel free to ask again and give more information.