Question

Solve for e: (E/e)=(R+r)/r)

Answer 1

$\dfrac{E}{e}=\dfrac{R+r}{r}\Rightarrow\dfrac{e}{E}=\dfrac{r}{R+r}\qquad|\text{multiply both sides by}\ E\neq0\\\\\boxed{e=\dfrac{rE}{R+r}}$