John Lesdon rents a workshop for £50 per week and pays heating costs of £15 per week. He has to pay insurance which costs £5 per week. John makes soft toys all of the same size and the costs for each toy are £2 for covering materials. 50p for stuffing materials and 20p for items such as eyes and mouths to sew on. What is the total cost for each toy if John makes 70 toys in a week? What is the total cost if John makes 100 toys in a week? Why do these figures differ?