Show with a proof by cases that for any x, y, z ∈ Q, max(max(x, y), z) = max(x, max(y, z)). How do I do this exercise?

B-simple yes/no questions

Volume is length times width times height so
20 times 8 times 30 which is 4,800
surface area is ph (p is perimeter of base), h is height.
so perimeter would be length+length+width+width so 20+20+8+8 which is 56. so multiply 56 times 30 which is 1680. hope this !