10. Melissa recently paid $400 for round-trip airfare to San Francisco to attend a business conference for three days. Melissa also paid the following expenses: $250 fee to register for the conference, $300 per night for three nights' lodging, $200 for meals in restaurants, and $150 for cab fare.

Note: Do not round intermediate calculations. Round your final answers to the nearest whole dollar amount. Leave no answers blank. Enter zero if applicable.

a. What amount of these costs can Melissa deduct as business expenses?

b. Suppose that while Melissa was on the coast, she also spent two days sightseeing the national parks in the area. To do the sightseeing, she paid $1,000 for transportation, $800 for lodging, and $450 for meals during this part of her trip, which she considers personal in nature. What amount of the total costs can Melissa deduct as business expenses?

c. Suppose that Melissa made the trip to San Francisco primarily to visit the national parks and only attended the business conference as an incidental benefit of being present on the coast at that time. What amount of the airfare can Melissa deduct as a business expense?