Can use Algebra, but I'm told is straight forward as a Calculus Problem:

A rectangular page is designed to contain 72 square inches of print. The margins at the top and bottom of the page are each 4 inches deep. The margins on each side are 2 inches wide. The dimensions of page are such that the least possible amount of paper is used.

Thus the width of the page is( ) inches, its height is ( )inches, its total area is ( ) square inches. There's a whole lot of white space on that page, its minimum area not withstanding!