Claire went into a movie theatre and bought 9 bags of popcorn and 2 pretzels costing a total of 80$ Melanie went into the same movie and bought 7 bags of popcorn and 4 pretzels costing a total of 72$ write a system of equations that could be used to determine the price of each bag of popcorn and the price of each pretzels define the variables that you use to write the system