This manual describes the mathematical foundations of decision-making, the methodology for constructing mathematical models of operations and decision-making for single- and multi-criteria problems, the most common informal decision-making methods in conditions of uncertainty and conflict situations are considered. The most studied and simplest of the conflicts are described - matrix games. Elements of the theory of statistical solutions, methods for solving problems of unconditional and conditional optimization are given. The manual is intended for students of specialties "Mathematical Methods in Economics," "Applied Mathematics," "Applied Mathematics and Computer Science," is recommended for students of economic specialties and will be useful for specialists involved in the justification of decision-making.