Equivalent Equations: Equations that have the same solutions.

Suppose each audio CD costs $12.00 at
a certain store. An equation to determine the change due from a $50.00 bill for
the number of CDs you want to purchase is:

c = 50 -
12n

c is a variable representing the
change due and n is the variable representing the number of
CDs purchased. If you bought 1 CD, then the change is $38.00. If you bought 3
CDs, then the change is $14.00.

If you recieved $26.00 in change, then we can determine the
number of CDs purchased. Finding the number of CDs purchased in this instance is
called solving the equation. There are several ways to solve this equation. When
the equation is solved, the solution is 2 CDs purchased. We can show this
solution by replacing the variables with the respective numbers.