Okay, the topic of this problem is electric power.

The problem is to determine the missing quantity.

In this case, in the circuit, the missing quantity is the power.

So in the left hand side of the circuit, we have some complex circuit that yields

a -6 volts with the polarity as shown in the problem across this element 1.

Also, we're given in the problem that the current is equal to -4 amps flowing

back into the complex part of the circuit.

And again we're looking for the power and to determine what the power is and

whether it's absorbed or supplied power?

So in this problem we're going to look at the well known equation for

power, that is power is equal to voltage times current.