6. You are building a box with a square base and an open top. The material for the bottom of the box costs 5 dollars per square foot, and the material for the sides of the box costs 7 dollars per square foot. You need the box to have a volume of 50 cubic feet. What is the minimum cost to build the box? (a) (3 points) Determine the equation of the constraint / restriction for this question: Constraint / Restriction: (b) (5 points) Determine the equation of the function to be minimized, the objective function. Give your equation in terms of a SINGLE variable