A quantity that does not change.
Something that contains one or more variables and may contain operation symbols.
To ________ an algebraic expression, substitute a number for the variable and then find the value.
Operations that undo each other. Addition and subtraction are ______ ________. If an equation contains addition, solve it by subtracting from both sides to "undo" the addition.
An _______ is a mathematical statement that two expressions are equal. You can think of a correct equation as a balanced scale.
A letter or symbol that represents a quantity that can change.
Equations may contain variables. If a value for a variable makes an equation true, that value is a ______ of the equation.
An equation can be solved, but an __________ can only be simplified.