Expressions & Equations

What you’ll learn

• Variables represent unknown or changing quantities; expressions combine variables, numbers, and operations without an equals sign.
• Evaluating an expression means substitute given values and follow order of operations.
• Writing expressions from words requires careful order (e.g. “5 less than x” is $x - 5$).
• Equivalent expressions can be built with the distributive property and combining like terms.
• One-step equations are solved with a single inverse operation on both sides; always check by substitution.
• Inequality solutions are graphed on a number line with open or closed circles and shading in the correct direction.