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Can someone help me?

I only know that I should compare the United States with Germany, and that the answer is in the tip, but I do not know what to do :s

I only know that I should compare the United States with Germany, and that the answer is in the tip, but I do not know what to do

I'm standing at this level. I know what the shell and the number mean, but I do not know what else to do. Can someone help me? Does the answer have chemistry?