Chapter 2 - Equations, Inequalities, and Problem Solving - 2.2 Using the Principles Together - 2.2 Exercise Set - Page 94: 30

$x=-12$

Using the properties of equality, the solution to the given equation, $ 27-6x=99 $, is \begin{array}{l} -6x=99-27 \\\\ -6x=72 \\\\ x=\dfrac{72}{-6} \\\\ x=-12 .\end{array} Checking: \begin{array}{l} 27-6(-12)=99 \\\\ 27+72=99 \\\\ 99=99 \text{ (TRUE)} .\end{array} Hence, the solution is $ x=-12 .$