まぁいいか。
$bunsi[0] = 2;
$bunbo[0] = 5;
$bunsi[1] = 3;
$bunbo[1] = 4;

$a = $bunsi[0] / $bunbo[0] + $bunsi[1] / $bunbo[1];
echo $a;

ディレクトリ内の構造をツリー表示せよ。
aiueo
├a.txt
├kakikukeko
:├b.php