To find volume its base times height times width. As you can see, the figure is given three measurements already, but the figure isn't whole.
To solve this problem you will need to times 25 by 20 which is base times width. Then you will need to add 1+1 which is 2, to find the length. Now taking the product of 20 and 25 which is 4,100, multiply 4,100 by 2. The product is 8,200. But there is a missing volume and you must subtract that volume. The length is 1, the width is 1 and 1 times 1 is 1. Now the base is also 1 so 1 times 1 is 1. Now 8,200 minus 1 is 8,199. That is the answer. I apologize if I am incorrect.