What is algebra?

Algebra is fundamentally the way in which we can find out the value of some unknown element. So for example, if a salesman agrees to sell two apples for £10 algebra can help us find out how much one apple would cost as the value of one apple is currently our unknown element. 

This problem can be presented in an algebraic calculation as 2x = 10. Thus by using one of the rules of algebra that whatever happens to one side must happen to the other, we can divide two by both sides of the equation to identify how much one apple (1x) would cost. so 2x/2 = 10/2. This would produce x = 5. As algebra gets more complicated the fundamental principle remains the same, it is helping us to find some unknown element.