Chapter 1 - Introduction to Algebraic Expressions - 1.7 Multiplication and Division of Real Numbers - 1.7 Exercise Set - Page 58: 106

$\dfrac{5}{28}$

The given expression, $ \left( \dfrac{-2}{7} \right)\left( \dfrac{5}{-8} \right) $, simplifies to \begin{array}{l}\require{cancel} \dfrac{-2(5)}{7(-8)} \\\\= \dfrac{-10}{-56} \\\\= \dfrac{\cancel{-2}\cdot5}{\cancel{-2}\cdot28} \\\\= \dfrac{5}{28} .\end{array}