Англичане, помогите перевести ( только не переводчик)
The theory of supply is the theory of how much output firms choose to produce. The principal assumption of the supply theory is that the producer will maintain the level of output at which he maximizes his profit. Profit can be defined in terms of revenue and costs. Revenue is what the firm earns by selling goods or services in a given period such a year. Costs are the expenses which are necessary for producing and selling goods or services during the period. Profit is the revenue from selling the output minus the costs of inputs used.