Chapter 3 - Equations and Problem Solving - 3.4 - Equations Involving Parentheses and Fractional Forms - Problem Set 3.4 - Page 123: 22

$x=-13$

The distributive property allows us to distribute anything multiplied by something inside of the parenthesis to whatever is inside of the parenthesis. Thus, we distribute the -1 to everything inside of the first set of parenthesis and the -2 to everything inside of the second set of parenthesis, giving us the equation -x-7=-2x-20. We now simplify: $x-7=-20 \\\\ x=-13$