Superposition rule is used to solve a DC resistive circuit which has two independent voltage sources and four resistors.
Finding current by using superposition method. There are two independent sources, so we need to turn them off one by one and calculate their contributions.
A circuit with two independent and two dependent sources is solved by the superposition method. Independent sources are turned off one at a time and the contribution of the on source is calculated. Dependent sources should not be turned off.
A circuit with two voltage sources and two current sources is solved by the superposition method. The contribution of each source is calculated individually and the response is found by adding the contributions.