What goes up must come down and what goes in must come out? These rules describe two fundamentals laws of electronics in a way that is simple and easy to remember.
What goes up must come down? In a circuit with a 9 volt source, the 9 volts are divided over the components in that circuit. You never have any spare voltage.
What goes in must come out? If you have 5 milliampere (mA) going into a component, then you have 5 mA coming out of it too. If you have 9 mA going into several branches, when the branches connect again, the total current from the branches equals the 9 mA that went into them. Hope it is useful to you.