Consider an economy where the following four transactions occur within a single year:

1. A car manufacturer purchases steel for $10,000 to build a new car.
2. The manufacturer then sells the newly produced car to a consumer for $25,000.
3. The consumer sells their old, used car to a neighbor for $5,000.
4. A stay-at-home parent provides childcare services to their own family, which would be valued at $15,000 if it were a market transaction.

Analyze how each of these transactions would be treated in the calculation of this country's total output for the year. For each transaction, explain whether its value is included, excluded, or partially included, and provide the reasoning based on the principles of measuring a nation's economic activity.