Joan has a cat called Tibber. Every day Tibber is fed 2 sachets of wet food and 25 grams of dry food. For some time, Joan has bought the cat food from the local pet shop where one box of 12 sachets costs £12.00 and one 400 gram packet of dry food costs £4.00. Joan has now decided to buy all of the cat food from an online distributor. Four boxes, each of 24 sachets of wet food, will cost £62.40, and one 2 kilogram packet of dry food will cost £16.00.