If you have two resistors $R\_{A},R\_{B}$ connected in parallel with a battery, you can find the current that flows through one resistor ex.$R\_{A}$ using the current divider rule:

$$I\_{A}=\frac{V\_{T}}{R\_{A}}$$
Hence:
$$I\_{A}=\frac{I\_{T}R\_{B}}{R\_{A}+{R\_{B}}}$$

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> As far as I understand, this rule holds because the voltage drop in each resistor is equal to the total voltage of the source $V\_{T}$, but why do I find books that apply it even if it is not?
>  Take for example this circuit: Why does the rule apply for finding the current that passes through $R\_{2}$ for example, even though its voltage drop isn't equal to the voltage of the battery?
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[![Circuit](https://i.stack.imgur.com/flBrT.png)](https://i.stack.imgur.com/flBrT.png)