Chapter 10 - Exponents and Radicals - 10.2 Rational Numbers as Exponents - 10.2 Exercise Set - Page 641: 106

$y\lt\dfrac{6}{5}$

Using the properties of inequality, then \begin{array}{l}\require{cancel} 10-5y\gt4 \\\\ -5y\gt4-10 \\\\ -5y\gt-6 .\end{array} Dividing both sides by a negative number (and consequently reversing the inequality symbol), then \begin{array}{l}\require{cancel} -5y\gt-6 \\\\ y\lt\dfrac{-6}{-5} \\\\ y\lt\dfrac{6}{5} .\end{array}