Andrew's annual salary as an accountant is $150,000, and his financial assets generate $14,000 per year in interest. One day, he decides to be his own boss, quits his job and uses his financial assets to establish a consulting business, which he runs out of his home. He spends $60,000 in cash to cover all the costs involved with running the business, and earns revenues of $160,000. What are Andrew's implicit costs?