Chapter 2 - Functions, Equations, and Graphs - 2-4 More About Linear Equations - Practice and Problem-Solving Exercises - Page 86: 22

$x-2y=4$

Using the properties of equality, in the form $Ax+By=C$ or the Standard Form of Linear Equations, the given equation is equivalent to: \begin{align*} -\dfrac{1}{2}x+y&=-2 \\\\ -2\left( -\dfrac{1}{2}x+y \right)&=(-2)(-2) \\\\ x-2y&=4 .\end{align*}