Frank bought 6 bags of dog food and 7 bags of cat food for $74.50. Daisy bought 3 bags of dog food and 9 bags of cat food for $ 67.50 . How much does it cost for each bag of dog and cat food ?

The price of a dozen eggs was $1.63. suppose the price increases m dollars per dozen and then the price decreases $0.12 per dozen. which expression represents the current price of eggs after the two price changes?