Cramers Rule

Format:<br>
Ax + By = E<br>
Cx + Dy = F<br>
Where A-F = already known numbers preceding variables<br>
and x-y = the variables you're want to find the value of.
<?
function calc($a, $b, $c, $d, $e, $f){
$numbers = array(1 => $a, 2 => $b, 3 => $c, 4 => $d, 5 => $e, 6 => $f);

for($x=1; $x < 7; $x++){
	$slash = strpos($numbers[$x], "/");
	if($slash !== false){
		list($y, $z) = explode("/", $numbers[$x]);
		$numbers[$x] = $y / $z;
		$numbers[$x] = round($numbers[$x], 20);
	}
}
	$answer[0] = ($numbers[1] * $numbers[4]) - ($numbers[3] * $numbers[2]);
	echo "$numbers[1] $numbers[2]<br>
		  $numbers[3] $numbers[4]<br>";
	echo "Array: $answer[0]<p>";
	
	$answer[0] = ($numbers[5] * $numbers[4]) - ($numbers[6] * $numbers[2]);
	echo "$numbers[5] $numbers[2]<br>
		  $numbers[6] $numbers[4]<br>";
	echo "X-array: $answer[0]<p>";
	
	$answer[0] = ($numbers[1] * $numbers[6]) - ($numbers[3] * $numbers[5]);
	echo "$numbers[1] $numbers[5]<br>
		  $numbers[3] $numbers[6]<br>";
	echo "Y-array: $answer[0]<p>";
	
	$answer[0] = $numbers[1] * $numbers[4];
	$answer['b'] = $answer[0] - ($numbers[3] * $numbers[2]);
	if($answer['b'] == 0){
		die("Invalid Input, A-D cannot equal 0");
	}
	
	$answer[1] = $numbers[5] * $numbers[4];
	$answer[2] = $answer[1] - ($numbers[6] * $numbers[2]);
	$answer['x'] = $answer[2] / $answer['b'];
	$answer['x'] = round($answer['x'], 10);
	
	$answer[3] = $numbers[1] * $numbers[6];
	$answer[4] =  $answer[3] - ($numbers[3] * $numbers[5]);
	$answer['y'] = $answer[4] / $answer['b'];
	$answer['y'] = round($answer['y'], 10);
		
	echo "X = $answer[x]<br>
		  Y = $answer[y]";
}
?>
<form method=POST action="z_calc.php" name="calculator">
 <table>
  <tr>
    <td>A:</td>
    <td>
	<input type="text" name="a">
	</td>
    <td>B:</td>
    <td>
	<input type="text" name="b">
	</td>
	<td rowspan=2>=<br>=</td>
	<td>E:</td>
	<td>
	<input type="text" name="e">
	</td>
  </tr>
  <tr>
   <td height="26">C:</td>
	<td>
	<input type="text" name="c">
	</td>
    <td>D:</td>
	<td>
	<input type="text" name="d">
	</td>
	<td>F:</td>
	<td>
	<input type="text" name="f">
	</td>
  </tr>
  <tr>
    <td colspan=7 align="center">
	<input type="submit" name="submit" value="Submit">
	<input type="reset" value="Reset">
	</td>
  </tr>
</table>
</form>
<?
if(isset($_POST['submit'])){
	calc($_POST['a'], $_POST['b'], $_POST['c'], $_POST['d'], $_POST['e'], $_POST['f']);
}
?>