<?phpclass baseCalc{ var $num1 = 5; var $num2 = 6; function calculate() { echo "$this->num1 is the first number<br />"; echo "$this->num2 is the second number<br />"; } } class addCalc extends baseCalc { function calculate() { var $num3 = $num1 + $num2; echo "$this->num1 plus $this->num2 equals $this->num3<br />"; } } class subCalc extends baseCalc { function calculate() { var $num3 = $num1 - $num2; echo "$this->num1 minus $this->num2 equals $this->num3<br />"; } } class mulCalc extends baseCalc { function calculate() { var $num3 = $num1 * $num2; echo "$this->num1 times $this->num2 equals $this->num3<br />"; } } class divCalc extends baseCalc { function calculate() { var $num3 = $num1 / $num2; echo "$this->num1 divided by $this->num2 equals $this->num3<br />"; } }$object1 = new baseCalc();$object1 -> calculate();$object2 = new addCalc();$object2 -> calculate();?>