To find the answer to question 4 find the volume of a rectangular prism. L x W x H (Length x Width x height) so the one on the top is 15 x 8 x 6. Then the one in the middle would be 15 x 16 x 6. Then the one on the bottom would be 15 x 24 x 6. Add those all together and you get the answer to question 4.
