Xenia is ordering a cake and she needs to feed 110 guests which will each guest will have a slice which is 4 inches by 4 inches she wants a squared three layered cake which size should she order

if xenia was really ordering a cake for a wedding she would be with a professional planner and know that you aren't ONLY concerned about the guests but the topper and decor as well. homework should be labeled as such and you might get more help. 

tell the pastry chef you want a cake that feeds 110 people with a freezable topper, they will know what to do!