Natalie is having a party and wants to order some pizzas. there will be 57 guests and she wants to ensure everyone gets a piece of pizza. he wants to pay the lowest possible amount and wants everyone to get an equal share. small pizzas are 20 cm; serve 12 people and cost 13.50 per pizza while the large one is 25 cms serves 20 peole and costs 18.75. how much will she have to pay for her order?