1. The problem statement, all variables and given/known data A rectangular storage container with an open top is to have a volume of 10 m^3. The length of this base is twice the width. Material for the base costs $10 per square meter. Material for the sides costs $6 per square meter. Find the cost of materials for the cheapest such container. 2. Relevant equations See below 3. The attempt at a solution I have my worked out (but wrong) solution here: http://img510.imageshack.us/img510/7963/calchw.jpg [Broken] For some reason I keep getting a negative answer. I really have no idea what I'm doing wrong.