The topic of this problem is Series and Parallel Independent Sources,

and the problem is to determine the current in the circuit that's drawn and

the power associated with the 5 ohm resistor.

In this problem, we have a series combination of voltage sources and

resistors.

And we know that we can combine series voltage sources by adding them,

and so that's what we're going to do in this problem.

We first of all acknowledge that the 5 volt sources,

all three of them are in series with one another, and we combine those, and

we get a 15 volt source as shown in the redrawn circuit.

And the way that we get that is by going clockwise around the circuit with

the negative polarity of the 5 volts source on the right hand side first,

that's minus 5 volts, we could continue in the top part of the circuit,

we hit the negative polarity of the 5 volt source at the top.

So, it's a minus 10 volts combining those two and

continuing around the circuit in clockwise fashion,

we hit the negative polarity of the 5 volt source on the right-hand side.

So that's how we ended up the 15 volt source

on the left-hand side of our redrawn circuit.