You first calculate the surface area of each box. Formula: 2(a*b) + 2(b*c) + 2(a*c)
Box 1: 2(21 x 21) + 2(21 x 21) + 2(21 x 21)
2(441) + 2(441) + 2(441)
882 + 882 + 882
2,646 cm squared
Box 2: 2(32x16) + 2(16x8) + 2(32x8)
2(512) + 2(128) + 2(256)
1024 + 256 + 512
1,792 cm squared
Now you know the surface area of both boxes. Box 1 would take more material so Box 2 is the answer. Now you need to find out by how much. Subtract the smaller box's surface area from the bigger box's surface area.
2,646 - 1,792 = 854
Box 2 needs 854 cm squared of material less than Box 1.
Answer: Box 2, 854 cm squared
