How to calculate gud will (

Good will is valued as two years purchase of the average profits of three previous years are Rs. 15000, the value of good-will be: (a) (b) Rs. 15000 Rs. 30000 (T) (c) Rs. 20000 (d) Rs 50000 Value of good will agreed upon Rs. 30000 on C.S admission and allowing him 4 share of total profit Good will is brought in cash, the amount of good-will be as: (a) (b) Rs. 7500 (T) (C) Rs Rs. 300000 150000 (d) RS. 120000