@1 - Các phép toán cơ bản: +, -, *, / NỐI CHUỖI ".$biến."

<?php
$a=8;
$b=2;
echo "<table width='600' border='1'>";
echo "<tr><td></td><td>+</td><td>-</td><td>*</td><td>/</td></tr>";
echo "<tr><td>a=$a</td><td rowspan='2'>".($a+$b)."</td><td rowspan='2'>".($a-$b)."</td><td rowspan='2'>".($a*$b)."</td><td rowspan='2'>".($a/$b)."</td></tr>";
echo "<tr><td>b=$b</td></tr>";
echo "</table>";
?>