Chapter 4 - Proportions, Percents, and Solving Inequalities - 4.1 - Ratios and Proportions - Problem Set 4.1 - Page 149: 36

$x=-37$

Using cross-multiplication, the value of the variable that satisfies the given equation, $ \dfrac{-9}{x+1}=\dfrac{-8}{x+5} ,$ is \begin{array}{l}\require{cancel} -9(x+5)=-8(x+1) \\\\ -9x-45=-8x-8 \\\\ -9x+8x=-8+45 \\\\ -x=37 \\\\ x=-37 .\end{array}