Problem+of+the+week

Jenny and Carly go shopping for shoes. Jenny chooses one pair for $110 and another for $100. Carly chooses a pair that costs $160. When they go to pay, the assistant says that there is a sale on and they get 3 pairs of shoes for the price of 2 pairs. Give two options for how much Jenny and Carly should each pay? Explain which option is fairer.