The topic of this problem is electric power. The problem is to determine the missing quantity. In this case it is the power in this circuit. So on the left hand side of the circuit we have some complex circuit that ultimately yields a voltage of 4 volts across this element, element 1 in the circuit. And we'll also find this complex circuit delivers a current of -3A to this element 1 as well. And what we're looking for, again, is the power, the power that is either absorbed or supplied by this element. Power, when it's absorbed, is a positive quantity. So if we, in the end, do the calculation and we end up with a power that's positive, then it's absorbed power. If we do the same calculation and it's a negative power that we end up with, then it's a supplied power. So in this problem, we're going to solve it by using the well-known equation for power, P=VI. And so in our case, the voltage across this element 1 is going to be + to -4V. And if we put that into our equation, we have (4V) for the voltage and we have (-3A) for the current, it's given in the problem statement. And so, that results in a -12 watts, Of power, and since it's a negative quantity, this power is supplied. So we have (12w of power supplied) by element 1.