If john is making a chest that we know is 1200 cubic inches, we can better understand this problem.
V = LxWxH remember?
So, if we multiply 20 and 12, and divide that product by 1200, and multiply the quotient of that and 20 and 12.. you have your answer! If you do not understand I will do it for you.
20x12=240 right?
1200 divided by 240= 5 right?
20x12x5= 1200.
Understand? :)
