I have Found A question in PHP and can’t Understand the idea of it

Write a PHP program that accepts three integer values and return true if one of them is 20 or more and less than the subtraction of others. and Sample Output: Input the first number : 15
Input the second number: 20
Input the third number : 25
false

Answer

Assuming that you are running the PHP thru a browser. Then the following codes should meet your needs

1. check whether one of them is 20 or more and
2. check whether it is less than the subtraction of others

<?php
$result = "Please enter data and click CHECK";

if (isset($_POST['submit']))
{

$var1=$_POST["var1"];
$var2=$_POST["var2"];
$var3=$_POST["var3"];

    $goodresult = 0;

    if ($var1 >= 20 && abs($var2 - $var3) > $var1)
    {
        $goodresult++;
    }

    if ($var2 >= 20 && abs($var1 - $var3) > $var2)
    {
        $goodresult++;
    }

    if ($var3 >= 20 && abs($var1 - $var2) > $var3)
    {
        $goodresult++;
    }

    if ($goodresult != 0)
    {
        $result = "Test is positive";
    }
    else
    {
        $result = "Test is negative";
    }
}
?>



<form action="" method=POST>

<table border=0>
<tr><td>First value: <td><input name=var1 value="<?php echo $_POST["var1"]; ?>"><br>
<tr><td>Second value: <td><input name=var2 value="<?php echo $_POST["var2"]; ?>"><br>
<tr><td>Third value: <td><input name=var3 value="<?php echo $_POST["var3"]; ?>"><br>
<tr><td colspan=2><input type=submit name=submit value="Check">
</table>
<?php echo $result; ?>

</form>