1st April, 2019, an existing firm had assets of   75,000 including cash of   5,000. Its creditors amounted to   5,000 on that date. The firm had a Reserve of   10,000 while Partners'   Capital Accounts showed a balance of 60,000. If Normal Rate of Return is 20% and goodwill of the firm is valued at 24,000 at four years' purchase of super profit, find average profit per year of the existing firm.