The volume formula for any 4 sided figure is V = l*w*h. If you have a side length measuring 27, and you cut out 2 corners measuring x, your side length measure is (27-2x). If you have a width measure of 18 and you cut out 2 corners measuring x, your width measure is (18-2x). If you fold up each of those cut out corners, you get the height. That height is what we cut away, "x". So the volume will be represented by (27-2x)(18-2x)(x)
