Susan Brown
You’ve got it!
In a series circuit, the current is the same at any point in the circuit, so you have to use the total resistance (all resistances added up) to calculate the circuit current.
Knowing the current, you can then calculate the power/heat across any load, or the voltage drop, if that’s what you are asked to find.
(Note: I’m going to hide the last part of your answer, so we don’t just give it away to other students.)