Chapter 2 - Equations, Inequalities, and Problem Solving - 2.2 Using the Principles Together - 2.2 Exercise Set - Page 94: 35

$a=-\dfrac{25}{2}$

Using the properties of equality, the solution to the given equation, $ -\dfrac{4a}{5}-8=2 $, is \begin{array}{l} -\dfrac{4a}{5}=2+8 \\\\ -\dfrac{4a}{5}=10 \\\\ a=10\cdot\dfrac{-5}{4} \\\\ a=\dfrac{-50}{4} \\\\ a=-\dfrac{25}{2} .\end{array}