Marvin is a famous Snow skier, and he receives the following amounts:

• A $19,000 bonus for being selected to ski on the Australian team at the next winter Olympics.
• $20,000 in prize money from the Australian Ski Association for being the best-performing skier for the season
• A perpetual trophy valued at $8,000

Required: Give a brief explanation to calculate his total assessable income. Apply the relevant principles in your answer.