Chapter 5 - Exponents and Polynomials - 5.2 - Multiplying Monomials - Problem Set 5.2 - Page 201: 64

$5x-26y$

Using $a(b+c)=ab+ac$, or the Distributive Property, and then combining like terms, the given expression, $ 2(5x-3y)-5(x+4y) ,$ simplifies to \begin{array}{l}\require{cancel} 10x-6y-5x-20y \\\\= (10x-5x)+(-6y-20y) \\\\= 5x-26y .\end{array}