The topic of this problem is Electric Power. The problem is to determine the missing quantity, the power, and the second element. We're giving at the power in the first element is equal to 36 watts and its absorb power. So we have 36 watts absorbed into element one. So if that's the case, then we know that using this well known equation for power is equal to voltage times current, that the current in element one is going to be Is equal to the power divided by the voltage. And that's equal to 36 watts divided by 12 volts. And we also know that power is positive, so that means that our current is going to be positive flowing back in to the complex part of the circuit, so that if it were flowing through this circuit in this manner will be flowing through this direction and the positive of the current would go into the positive polarity across element one. So it's the positive current hitting the positive polarity if the element one voltage which is 12 volts. And so, the current in this case is going to be 3 amps. 3 amps of current flowing back into the complex circuit at the top of the circuit. The problem is to determine what the power across the circuit element is and whether it's absorb power or if it's supplied power. We already know the current, we determine that from the information were given about element one. That is it had 12 volts across it with the polarity shown and have 36 watts of the absorbed power. We know that sensors absorb, it's a positive power. And so that leads us to find the current. Is in the direction toward the complex circuit and is a positive 3 amps. And if that's the case, that positive 3 amps is also flowing through element two from the bottom to the top. And so for element two, P2 is going to be the current, 3 amps and the voltage which is minus 4 volts. The reason we chose minus 4 volts is because, if you look at the current, the current is flowing into the bottom side of element two or the polarity is negative, so the negative side of the 4 voltage drop across element two gives us the minus sign in front of the four volts. And so we end up in this case with 12 watts, minus 12 watts of power, and that means that we have 12 watts of supplied power from element two.