According to the All Math website, algebra is the area of math "dealing in representing numbers with letters." Understanding algebra is the basis for learning and applying higher-level math such as calculus and physics. Algebra is on both the SAT and GED tests. Occupations that require a mastery of algebra include electronics, engineering, computer science, medical research and analysts. All algebra concepts build in this basic mathematical linear equation: X + A = B, where A and B are known quantities.

Rewrite the equation using the given numbers for A and B. For this example, the equation is X + A = B, where A= 5 and B = 9. Rewritten, the equation is X + 5 = 9. X in this equation is known as the variable.

Subtract the same amount from each side of the equation so that X (the variable) is on one side of the equation and the known numbers are on the other side. For our example: X + 5 - 5 = 9 - 5. Working the math, the equation now reads X = 4.

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Replace X with your answer in the original algebraic equation to see if the solution is correct. X + 5 = 9, where X = 4 is rewritten 4 + 5 = 9. Because 4 + 5 does equal 9, you can be sure you found the correct X factor for this equation.