12. The cost $C of a company is partly constant and partly varies directly as the total number of employees n. It is given that the cost of 50 employees is $52,500 and that of 25 employees is $27,500. (a) Express C in terms of n. ( 9 marks) (b) Find the cost of a company when it has 80 employees. (3 marks) (c) Find the number of employees if the cost of a company is $12500