One of the most common algebraic symbols is the use of x, y or another letter of the alphabet to indicate a variable or unknown quantity. Common symbols used in algebra also include those related to equality, inequality, factorials and organization, like braces, brackets and parentheses.
X is a variable that represents an unknown number. To get the unknown number in the example you need to divide 15 by 5 and 5 by 5 to get X alone and then X will equal 3.
