Here's the problem:

A sheet of metal is 29.4 mm wide and 16.1 mm long. If it weighs 4.093 g and the density of the metal is 7.23 g/cm3, what is the thickness of the sheet (in mm)?

I'm not sure how I would begin to approach a problem like this as it's asking for a variable I'm not sure how to solve down for. Any help towards this problem will be more then appreciated, thank you. :)