A variable is simply any symbol that replaces a value, most likely one that is unknown.
Examples: ☺ x b ¥ a
Solving:
To solve for variables, it is very simple. In most cases, this will probably be done in the fashion of one- or two-step equations. First, you would need to isolate the variable to one side of the equivalent sign, if there are variables on both sides. After that, you need to eliminate constant terms, leaving the variable and coefficient alone on one side and on the other is the product of the variable and coefficient. Now, you would need to divide both sides of the equal sign by the coefficient, leaving the variable alone with it's variable there.
From here, it is a good idea, but not completely necessary to check your answer. All you would need to do in this case is rewrite the equation, substituting the variable in every case possible for the value of the variable. Solve as normal, and make sure the answer is equivalent to the original.
Solving for multiple variables:
In this situation, with variables on both or even just one side of an equal sign, it would not be possible to find exact values.
However, if there is already a given value for one of the variables, refer to middle of the page for solving