so for the first one you do 18.25^3 which is 6,078.39 cubic inches , the reason it's cubic is volume is always cubic , for the second one square is related to the area while cube is volume. I hope it helps :)
I'm sorry I really don't know I'm not really good with math that's why I got them brainly for other people's help because I really not that cool math and I'm homeschooled