<?php
$i=19;
if(in_array($i, range(10, 18))){
 echo 'aaaaa';
}elseif(in_array($i, range(20, 25)){
 echo 'iiiii';
}else{
 echo 'uuuuu';
};?>

<?php
$i = 19;
if( $i => 10 && $i <= 18 ){
   echo "kumaaaa";
}else if( 20 <= $i && $i <= 25){
   echo "TUNAAAAAA";
}else{
   echo "syakeeee";
}
;?>