The document defines and discusses linear equations in one variable. It begins by defining an equation as a statement that two algebraic expressions are equal. It then defines a linear equation in one variable as an equation involving only one variable of the first degree. The document goes on to list properties of equations and methods for solving different types of linear equations in one variable, including using addition/subtraction, multiplication/division, and transposing terms. It also provides examples of solving word problems involving linear equations.