Equations are made up of two expressions on either side of an equals sign, such as:
\[x + 1 = 2\]
To solve an equation, you aim to find the value of the missing number.
'I think of a number, add four, and the answer is seven.'
Written algebraically, this statement is \(x + 4 = 7\), where \(x\) represents the number you thought of.
\(x + 4 = 7\) is an example of an algebraic equation where \(x\) represents the unknown number.
The number you first thought of must be three (\(3 + 4 = 7\)). Therefore, \(x = 3\) is the solution to the equation \(x + 4 = 7\).