What is the current through the battery if the switch S is opened

So, our current when our switch is open is going to be equal to the voltage across the resistors, and that's going to be our 12 volts, 12 volts, divided by the equivalent resistance of these resistors. When the switch is open, essentially, we just have R1 and R2 in series, and so this is just gonna be R1+R2.

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