Question

Solve the equation E = V + Ir for r.

Answer 1

The given equation is

$E=V+lr$

First, subtract V from each side.

$\begin{gathered} E-V=V-V+lr \\ E-V=lr \end{gathered}$

Second, divide each side by l.

$\begin{gathered} \frac{E-V}{l}=\frac{lr}{l} \\ r=\frac{E-V}{l} \end{gathered}$

Therefore, the answer is

$r=\frac{E-V}{l}$