Chapter 1 - Some Basic Concepts of Arithmetic and Algebra - 1.5 - Use of Properties - Problem Set 1.5 - Page 34: 76

$230$

Combining like terms, the given expression, $ -9x+xy-4xy-x ,$ simplifies to \begin{array}{l}\require{cancel} (-9x-x)+(xy-4xy) \\\\= -10x-3xy .\end{array} Substituting $ x=10 $ and $ y=-11 ,$ the resulting expression above evaluates to \begin{array}{l}\require{cancel} -10(10)-3(10)(-11) \\\\= -100+330 \\\\= 230 .\end{array}