In january of 2018, the phillips company purchased a patent at a cost of $100,000. in addition, $10,000 in legal fees were paid to acquire the patent. the company estimated a 10-year useful life for the patent and uses the straight-line amortization method for intangible assets. in 2020, phillips spent $25,000 in legal fees for an unsuccessful defense of the patent. the amount charged to income (expense and loss) in 2018 related to the patent should be:

Atennis club charges a monthly membership fee of $150 and charges it members $10 per hour to use a court. there's also $500 fee to become a member. stella joined the tennis club last spring, and she has been a member for 5 months. she has been playing 10 hours of tennis each month. stella values an hour of her time at $20. during a boring afternoon meeting, stella thinks about reserving a court to work on her serve for an hour tonight. what's stella's opportunity cost of working on her serve for an hour?