A rectangular nutritious cake with a length of 30cm, a width of 20cm and a height of15cm is divided into three small cuboid cakes. What is the total surface area of three cakes? What's the minimum? Maximum value (30× 20+30×15+20×15) × 2+30× 20× 4 = (600+450+300 )× 2+2400 = 2700+2400 = 5650.