Final answer:
Producer surplus in a perfectly competitive industry is the difference between total revenue and total cost.
Step-by-step explanation:
A perfectly competitive firm in a perfectly competitive industry can determine its producer surplus by finding the difference between total revenue and total cost. Producer surplus represents the amount of profit that a firm makes by producing and selling goods or services in a competitive market.
For example, if a firm's total revenue is $1,000 and its total cost is $800, then the producer surplus would be $200. This surplus represents the profit that the firm has earned above its costs.