The expense of a boarding house is partly fixed and partly varies with the number of boarders. What is the profit per head per month when there are 80 boarders? Which one of the following is correct in respect of the Question and the Statements given below? Statement 1: Each boarder pays $ 780 a month. Statement 2: The profit is $108 per head per month when there are 50 boarders. Statement 3: The profit is $128 per head per month when there are 60 boarders.