A company makes three sizes of cardboard boxes: small, medium, and large. It costs $3.50 to make a small box, $5.00 for a medium box, and $5.50 for a large box. Fixed costs are $8000. (a) Express the cost of making x small boxes, y medium boxes, and z large boxes as a function of three variables: C (x, y, z). f(x, y, z) = (b) Find (6000, 9000, 8000). Interpret your answer. It costs the company $ to make 6000 small boxes, 9000 medium boxes, and 8000 large boxes. (c) What is the domain of f? Ox0,-sys, zo O-sxs, -sys, - Oxso, y 0, z0 Ox0, y 0, z0 -sxs, y 0, 20