A married couple send their children to a private school and pay $$24,000$ for tuition. They also pay $$9,500$ of real estate taxes to the local government to fund the public school system. Should this couple be exempt from paying the real estate taxes? I know that they should no be exempt from Paying real Estate Taxes, but I do not know how to explain it in detail why and Specially, how to address what are the characteristics that determine that a payment is a tax.