A closed rectangular bos with a volume of 16cu. ft is made from 2 kinds of materials. the top and bottom are made of material costing 10cents per square foot and the sides of the material costing 5censts per sqaure foot. what r the dimenstions of the box so that the cost of the materials is minimized. How do I go about starting this. I was able to solve a similar one regarding maximizing the volume of a box, nothing with cost though. any help is appreciated.