Ok so u multiply the numbers by 2 since 5x2 =10 so u do that to the top num and bottom so
5x2 and 4x2 and then replace the4/5 with the answers you get
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.
10 lb
well I could be wrong