3x −4 is an example of an algebraic expression.
3x −4 = 2 is an example of an algebraic equation (i.e. it contains an ‘=’ sign). An equation is simply a statement that two expressions are equal.
To ‘solve an equation’ means ‘to find the value of the unknown’. For example, solving 3x −4 = 2 means that the value of x is required. In this example, x = 2.
Note: We can do anything we like to an equation, as long as we do the same to both sides.