An equation is a statement of equality: Whatever is on the left-hand side of any equation is equal to whatever is on the right-hand side. The symbols in an algebraic equation usually cannot have arbitrary values if the equality is to hold. To solve an equation is to find the possible values of these symbols. The solution of the equation 5x − 10 = 20 is x = 6 because this is the only value of x for which this equation is a true statement. The algebraic procedures that can be used to solve an equation are all based on the principle that any operation.
