How to find percentage of result with php+mysql ?

I am trying to display a percentage of a result on my webpage.

I have managed to get the result numers of: 50.0 and 90.0

But do not know the code to add to the query to take off 20% so I can also display the numbers:40.0 and 72.0 ?

 

$p = 50;

$discounted_price = $p - ($p*.20);

$p is the pre discount price

 

Many thanks Phynder

 

I have managed to get this working on all pages except the results page of a search form,anyone any ideas ?

This is my results page:

 $search = "%" . $_POST["search"] . "%";

  $result = "SELECT **,***,** FROM members WHERE ** LIKE '$search'";
  $result = mysql_query ($result);


    {
    while ($row = mysql_fetch_array ($result)) {

      echo $row[0] . "<b><br>";
 echo $row[1] ."\$<b><br>" ;
echo $row[2] ."\$<b><br>" ;
echo $row[3] ."<b><br><hr>" ;

    }
  }

?>

PHP:

I managed to get it working on all other pages like this:

$query="SELECT BAAR,foo FROM `mydatabase`ORDER BY foo DESC LIMIT 5";

$result=mysql_query($query);

$num=mysql_numrows($result);


mysql_close();

echo "<b><center></center></b><br><br>";

$i=0;
while ($i < $num) {


$domain=mysql_result($result,$i,"BAAR");
$cost=mysql_result($result,$i,"foo");
echo "<b>$domain<br>HOW MUCH($)$cost<hr><br>";
$p = "$cost";
$per = $p - ($p*.20);
$L = "$cost";
$low = $L - ($L*.80);
$i++;
}

?>

PHP:

As you can see above the 20% and 80% is not stored on the database I just need to do the math from the $cost result.
The problem I have is I am getting confused trying to play with the echo $row results in example one above.

Do I need to query the echo $row[1] result ?
($row[1]) is $cost

 

You can put math in sql itself and display results directly using echo $row[0]

example