A prism with square bases is just a square prism.
The volume of a rectangular prism is equal to its width times its length times its height. Since the base is a square, we can just say it's equal to the base squared times the height. Let's set up a formula, plug and chug.
[tex]V = b^2h \\ 5880 = 30b^2 \\ 196 = b^2 \\ \sqrt{196} = b \\ \boxed{14 = b}[/tex]
