We go through solving a circuit which only containes independent sources: two voltage sources and two current sources. KVL and KCL are used to determine voltages and currents.
Determine the amount of power absorbed or supplied by each source.
Solution
a) The current source keeps the current of the loop and the voltage source keeps the voltage across the current source as shown below. (more…)
Find the current passing through the voltage source:
a)
b)
Solution
a) The voltage source is in series with the current source. Since by definition a current source keeps the current passing through itself constant and the voltage source is in series with the current source, it should have the same current . (more…)
Find voltages across the current sources.
a)
b)
c)
d)
e)
Solution
In each case, the current source is parallel with a voltage source. Therefore, the voltage across the current source is equal to the voltage of the voltage source, regardless of other elements. (more…)
and the voltage source keeps the voltage across the current source 
as shown below.
.
supplying power.
and 
.
.