Chapter 5 - Exponents and Polynomials - 5.2 - Multiplying Monomials - Problem Set 5.2 - Page 201: 68

$-4x+6$

Using $a(b+c)=ab+ac$, or the Distributive Property, and then combining like terms, the given expression, $ 2[3x-(2x+1)]-2(3x-4) ,$ simplifies to \begin{array}{l}\require{cancel} 2[3x-2x-1]-6x+8 \\\\= 2[x-1]-6x+8 \\\\= 2x-2-6x+8 \\\\= (2x-6x)+(-2+8) \\\\= -4x+6 .\end{array}