## Intermediate Algebra (6th Edition)

$r=\frac{E-IR}{I}$
We are given that $E=I(r+r)$. We can use the distributive property to multiply out the terms on the right side. $E=I\times(r+r)=Ir+IR$ Subtract IR from both sides. $E-IR=Ir$ Divide both sides by I. $r=\frac{E-IR}{I}$