Chapter 3 - Equations and Problem Solving - 3.3 - More on Solving Equations and Problem Solving - Problem Set 3.3 - Page 114: 30

$n=-5$

Using the properties of equality and combining like terms, the value of the variable that satisfies the given equation, $ -3n+6+5n=7n-8n-9 ,$ is \begin{array}{l}\require{cancel} -3n+5n-7n+8n=-9-6 \\\\ 3n=-15 \\\\ n=\dfrac{-15}{3} \\\\ n=-5 .\end{array}