How should we find the surface area of the box? One could find the area of each side of the box, then add the values together. However, that would take a long time. There is an easier way. Remember our measurement for the area of the original piece of paper? 475, right? We used that same piece of paper to make our box. What did we change?
We cut 4 3x3 squares out of it. This box had a cut of 3. We'll call the cut "x," because we will change the size of the cut on Page 2. All that is different from the original box is the boxes that we cut out.
Therefore, we will have our surface area if we subtract the area we cut out from the area we started out with. To find the area we cut out, we must simply multiply 3 by 3 (or 32) to get the area of each cut out square, and then multiply that value by 4, or the number of these squares that we cut out.
This procedure can be represented as a formula: surface area= 475-4x2, where x is the length of the cut. You should find that the surface area is 439 square units.
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