A system of linear equations consists of two or more equations made up of two or more variables such that all equations in the system are considered simultaneously. The solution to a system of linear equations in two variables is an ordered pair that satisfies each equation independently. There are three primary forms of linear equations: point-slope form, standard form, and slope-intercept form.
To clue you in linear equation word problems usually involve some rate of change or steady increase (or decrease) based on a single variable. If you see the word rate, or even "per" or "each", it's a safe bet that a word problem is calling for a linear equation. Chapter 12 explains the method of solving equations, which contain fractions, transposing terms and word problems.