A company makes three sizes of cardboard boxes: small, medium, and large. It costs $2.50 to make a small box, $4.00 for a medium box, and $4.50 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 = f (x, y, z).
(b) Find f s3000, 5000, 4000d and interpret it.
(c) What is the domain of f ?