A box manufacturer makes boxes of volume 500cm3 from pieces of tin 20cm on a side by cutting squares from each corner and folding up the edges. Find the length of each side of a square.

From the above from, I found some steps in solving the above problem. However, I followed through, gotten the answer but couldn't make sense of it. The followings are how I did it:

First : since we know that it cut out squares from the corners, the side of the squares is x. Hence, the length would be 20-2x.

The formula to solve for x would be x(20-x)(20-x). Factoring everything, I will have the answer 5 and 1.9 or 13.09(13.09 is not in the answer sheet)

My questions are, isn't the box suppose to be a square? Why does it have different measurement of the sides 5 and 1.9? Secondly the formula for volume is l*b*h. With sides at 5 and 1.9, I wonder how do i get the volume of 500?