(только не переводчик) aiming to get higher profits, firm obtain each output level as cheaply as possible. firms choose the optimal output level to receive the highest profits. this decision can be described in terms of marginal cost and marginal revenue. marginal cost is the increase in total cost when one additional unit of output is produced. marginal revenue is the corresponding change in total revenue from selling one more unit of output.
Предельный доход я- это соответствующее изменение общей выручки от продажи еще одной единицы продукции.