The applications of optimization to economic problems have received considerable attention of scholars in recent decades. It refers to the selection of a best solution from a set of available alternatives. This study examines behavioral responses of consumers or firms when prices of inputs change. Specifically, the author minimizes the cost of a firm subject to output constraint, maximizes the output of a firm subject to budget constraint, maximizes the utility of an individual subject to multiple constraints assuming that during emergencies such as war or natural disaster consumers may pay for goods with money and surrender ration coupons, maximizes the utility of an individual subject to quadratic and cubic budget constraints encountered in daily life during quantity discounts offered by some markets/firms or quantity surcharge imposed by the regulation of governments, maximizes the output subject to nonlinear budget constraint assuming that firms get price discounts for purchasing larger quantities of inputs, and optimizes the social welfare of a community subject to utility maximization constraints and derives production functions in three commodity-three consumer economy.