Calculations

<?php

$command = strtolower(readline());
$a = intval(readline());
$b = intval(readline());

switch ($command){
    case 'add':
        $sum = printAdd($a, $b);
        echo $sum;
        break;
    case 'multiply':
         echo printMultiply($a, $b);
        break;
    case 'subtract':
        printSubtract($a, $b);
        break;
    case 'divide':
        printDivide($a, $b);
        break;
}

function printAdd($num1, $num2){
    $result = $num1 + $num2;
    return $result;
}
function printMultiply($num1, $num2){
    $result = ($num1 * $num2);
    return $result;
}
function printSubtract($num1, $num2){
    echo ($num1 - $num2);
}
function printDivide($num1, $num2){
    echo ($num1 / $num2);
}