Chapter 1 - Section 1.2 - Formulas and Percent - 1.2 Exercises - Page 62: 28

$y=\dfrac{1}{5}x+4$

Using the properties of equality, in terms of $ y ,$ the given equation, $ x-5y=-20 ,$ is equivalent to \begin{array}{l}\require{cancel} -5y=-x-20 \\\\ y=\dfrac{-1}{-5}x-\dfrac{20}{-5} \\\\ y=\dfrac{1}{5}x+4 .\end{array}