Acompany will make a cereal box with whole number dimensions and a volume of 100 cubic centimeters. if carboard cost $0.05 per 100 square cm, what is he least cost to make 100 boxes

Possible dimension of a box with a volume of 100 cubic cm
10 x 10 x 1 = 100
10 x 5 x 2 = 100
5 x 5 x 4 = 100

Surface area:
10 x 10 x 1 dimensions: 
10 x 10 = 100 x 2 = 200 sq.cm
10 x 1 = 10 x 4 = 40 sq. cm
240 sq. cm * $0.05 / 100 sq.cm = $0.12 per box
0.12 per box * 100 boxes = $12

10 x 5 x 2 dimension
10 x 5 = 50 x 2 = 100 sq. cm
10 x 2 = 20 x 2 = 40 sq. cm
5 x 2 = 10 x 2 = 20 sq. cm
160 sq. cm * $0.05/100 sq. cm = $0. 08 per box
0.08 per box * 100 boxes = $8

5 x 5 x 4 dimension
5 x 5 = 25 x 2 = 50 sq. cm
5 x 4 = 20 x 4 = 80 sq. cm
130 sq. cm * $0.05/100 sq. cm = $0.065 per box
0.065 per box * 100 boxes = $6.50

The best dimension to use to have the least cost to make 100 boxes is 5 x 5 x 4. It only costs $6.50 to make 100 boxes.