As of December 31, 2008, Johnstown Company has $50,000 in accounts payable, $100,000 in promissory notes payable in 5 years, $100,000 in cash, $50,000 in accounts receivable and $50,000 in property, plant and equipment. The company’s net income was $10,000 for 2008 and the company has no other assets or liabilities.

To determine the total assets and total liabilities of Johnstown Company as of December 31, 2008, we will need to classify the given information.

Assets are items of value owned by the company, either tangible or intangible. In this case, the given assets are:

1. Cash: $100,000
2. Accounts receivable: $50,000
3. Property, plant, and equipment: $50,000

Total assets = Cash + Accounts receivable + Property, plant, and equipment
Total assets = $100,000 + $50,000 + $50,000
Total assets = $200,000

Liabilities are the financial obligations or debts of the company. The given liabilities are:

1. Accounts payable: $50,000
2. Promissory notes payable in 5 years: $100,000

Total liabilities = Accounts payable + Promissory notes payable in 5 years
Total liabilities = $50,000 + $100,000
Total liabilities = $150,000

The net income represents the company's profit after deducting expenses from revenue. In this case, the net income for 2008 is $10,000.

Now, let's calculate the owner's equity. Owner's equity is the residual interest in the assets of a company after deducting liabilities. It can be calculated using the formula:

Owner's Equity = Total Assets - Total Liabilities
Owner's Equity = $200,000 - $150,000
Owner's Equity = $50,000

In this case, the owner's equity is $50,000.

To summarize:

Total Assets = $200,000
Total Liabilities = $150,000
Owner's Equity = $50,000