1. The number of equations to be composed must correspond to the number of unknowns. 2. When composing equations, it is necessary to ensure that each next equation contains at least one unknown quantity that was not included in the previous equations. 3. For each circuit, the direction of its bypass, which determines the signs of the currents and EMF, is chosen arbitrarily. If, as a result of solving the problem, a negative value is obtained for the current strength in some section, then this means that the current in this section goes in the direction opposite to the selected circuit bypass.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.