If GNP is $600 billion, receipts of factor income from the rest of the world are $50 billion, and payments of factor income to the rest of the world are $30 billion, then GDP is O $680 billion O $520 billion O $580 billion O $620 billion When you pay $8 for a salad you ordered for lunch, you are using money as a(n) O store of value investment good O medium of exchange O unit of account