Answer
$R_{3}=4590~\Omega$.
Work Step by Step
Given
$\frac{1}{R}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}}$
$R=1830~\Omega, R_{1}=4560~\Omega, R_{2}=9150~\Omega,R_{3}=?$
$\frac{1}{1830}=\frac{1}{4560}+\frac{1}{9150}+\frac{1}{R_{3}}$
$\frac{1}{R_{3}}=\frac{1}{1830}-(\frac{1}{4560}+\frac{1}{9150})$
Therefore, $R_{3}=4590~\Omega$
How to use the calculator:
$1830*x^{-1}-4560*x^{-1}-9150*x^{-1}=x^{-1}=$