Definitions Relating to Expressions
 A mathematical Expression is a combination of symbols that can designate numbers
(constants), variables, operations, symbols of grouping and other punctuation.
 Literal Numerals are letters that stand for numbers (e.g. a, b, x, y).
 A Constant represents a known value in an algebraic expression.
 A Variable is a symbol that represents a changeable or undetermined quantity in an algebraic expression.
 Operations include addition, subtraction, multiplication, division and exponentiation.
 Grouping Symbols include parentheses (), curly brackets {}, or square brackets [].

