How many square decimeters can the surface area increase at most and how many square decimeters can the surface area increase at least by sawing the wood below into two cuboids? It's 3 decimeters wide. OK, add points
The maximum surface area is 20 × 3 × 2 = 120 square decimeters
The minimum surface area is 2 × 3 × 2 = 12 square decimeters