// with arguments function addition($num_1, $num_2) { $num_3 = $num_1 + $num_2; return $num_3; } echo addition(20, 22) .'
'; // with default argument values function subtraction($num_1, $num_2 = 5) { $num_3 = $num_1 - $num_2; return $num_3; } echo subtraction(20, 10) .'
'; echo subtraction(20) .'
'; echo subtraction(220, 110) .'
';
Hello World!