An *algebraic equation,* as with the equations defined above, is a statement in which two numbers, letters, or expressions are equal. But algebraic equations take the idea even further: Most of the time, you are trying to simplify the numbers and one (or more) variables in the equation. They can further be defined as any combination of variables or constants linked together by any operation—addition, subtraction, multiplication, division (except division by zero). This type of algebraic equation is often referred to as a polynomial (see elsewhere in this chapter for more about polynomials).