Originally in the lesson on Voltage Drop the Master tells you the sum of all must equal the source,
This is Kirchoff’s Law of voltage drops. The key here is the SUM of all the various voltage DROPS across the loads (how ever many there are) must equal the source voltage SUPPLY. But the specific AMOUNT of voltage dropped across each load will be in direct proportion to the RESISTANCE of that load– the higher the load’s resistance, the more voltage it will drop compared to the other loads. But the SUM of all the voltage DROPS will always exactly equal the voltage SUPPLY, no more, no less.