So, using these two rules I can make all sorts of predictions about circuits. And in this case here I'm going to use them to predict what the current is going to be through this circuit here. So, let's see what do we know? I've got 9 volts on this side. So that means that at this point here I must still have 9 volts. And at this point here I'm at 0 volts. So, as the charges move across these are just to see they must lose 9 volts of energy. And I also know that the amount of current that's going into this resistor must be equal to the amount of current going out of this resistor because of the node rule. So, I know the current through each of these resistors must be the same. Let's put this into equations. I'm going to call this resistor, resistor 1, and this resistor resistor, resistor 2. And I know that the voltage drop across both resistors, so the voltage across resistor 1, plus the voltage drop across resistor 2, must be equal to 9 volts. And I also know from Ohm's law that the voltage across one of these resistors is going to be equal to the current times the resistance. So, in this case I would have. Then, using conservation of charge or the node rule, I know that the current going across resistor 1 must be equal to the current going across resistor 2, so I1 equals I2. So now I have a series of four equations. I can use all these equations together to find the current that's flowing through the circuit. So, first of all, I'm going to substitute, first of all, I'm going to substitute equation 2 and equation 3 into equation 1. So that will give me. And now, I'm going to substitute equation 4 to get rid of I1. So now, I can rearrange this to solve I2. And in this case, I know that both I1 and I2 are equal to 1 ohm each, so that gives me. I'm going to substitute 9 volts over 2 ohms, which is equal to 4.5 amps. So now, I've worked out the amount of current that is flowing through this circuit.