<?php function calculater($num1,$num1,$num2) { if ($sum == "+"){ return $num1 + $num2; }elseif ($sum == "-"){ return $num1 - $num2; }elseif ($sum == "*"){ return $num1 * $num2; }elseif ($sum == "/"){ return $num1 / $num2; }else{ echo"not true value" } } $number1 = 10; $number2 = 20; $sum="*"; echo calculater($number1,$number2,$sum); ?>