1) Define accounting profit and economic profit. When total sales revenue is $120,000, total costs $63,000, and total implicit costs is $33,000. Please calculate accounting profit and economic profit.

2) Define fixed costs and variable costs. Show actual examples of each cost. In economics, we categorize such kinds of costs based on short-run and long-run variable and fixed costs. Why we should consider the time variable when the costs are categorized?