Addition example: 5 + 100 = 105
Subtraction example: 5 - 100 = -95
Division example: 5 / 100 = 0.05
Multiplication example: 5 * 100 = 500

In the example above my variables were $x = 5 and $y = 100. The + operator gave the sum of $x and $y. The operator - gave the difference of $x and $y. The operator / gave the quotient of $x and $y. And the operator * gave the product of $x and $y.