Chapter R - Elementary Algebra Review - R.2 Equations, Inequalities, and Problem Solving - R.2 Exercise Set - Page 946: 18

$a=\dfrac{3}{8}$

Using the properties of equality, the value of the variable that satisfies the given expression, $ a+7-2a=14+7a-10 ,$ is \begin{array}{l}\require{cancel} a-2a-7a=14-10-7 \\\\ -8a=-3 \\\\ a=\dfrac{-3}{-8} \\\\ a=\dfrac{3}{8} .\end{array}