## Elementary Technical Mathematics

$$\approx 19$$
We find $R$ by dividing both sides by $I^2$ as follows: $$P=I ^2R\Longrightarrow \frac{P}{I^2}\Longrightarrow R=\frac{P}{I^2} .$$ Now, by substituting, we get $$R=\frac{480}{5^2}=\frac{96}{5}=19\frac{1}{5} \approx 19$$