Final answer:
The student's question involves calculating the firm's profit by finding the difference between total revenue and total cost at a given production quantity.
Step-by-step explanation:
The question is related to the concepts of total revenue, total cost, and profit calculation in the context of economics and business math. To determine the firm's profit, we can calculate the difference between total revenue and total cost for a given quantity of products sold.
For instance, at a quantity of 40 phones, if the total revenue is $640 and the total cost is $580, the profit is $640 - $580, which equals $60. Similarly, in a scenario where the firm sells 5 units at $25 each, the total revenue would be $125. If the total cost at this level of output is $130, the firm experiences a loss of $130 - $125, resulting in negative profits of $5. To maximize profits, the firm must find the quantity where the difference between total revenue and total cost is the largest.