<?php
$a = 10;
$b = 20;
$c = 30;
$d = 40;
if ($a == $b) {
    echo 'A is equal to B';
} elseif ($a == $c) {
    echo 'A is equal to C';
} elseif ($a == $d) {
    echo 'A is equal to D';
} else {
    echo 'A is actually not equal to anything';
}
?>

A is actually not equal to anything