First you will need to find the radius of the base of the can. We have the area so to find the radius you divide 40cm by Pi and then square root the results, which will leave us with 3.568cm. So the radius of the base is 3.568, now take that square it, times it by 12cm, and multiplay it by Pi which will leave you with the volume of the shape which is 479.93321800817 centimeters^3. Now with that being there use the simple mass formula which is Volume times density so the answer is 575.9198616098g. hope this helps