weird result!

[NachoF]

I was trying (long explanation as to why) to find out all the possible combinations to get below 9.5 but above 8.5 as the final grade of a course that consists on three tests, two quizes and points that you get only if you get 10 points or more(20 is the highest possible grade )on each test (0.5, 0.5 and 1 extra point respectively).... I tried this very simple algorithm but for odd reason the highest grade I get is 18, not 20..... it appears to not be adding the extra 0.5s and 1... any help appreciated.

 
<?php

for($i=0;$i<=20;$i++)
{
$definitiva=0;
  for ($j=0;$j<=20;$j++)
  {
  $definitiva=0;
    for ($k=0;$k<=20;$k++)
    {
    $definitiva=0;
      for ($l=0;$l<=20;$l++)
      {
      $definitiva=0;
        for ($m=0;$m<=20;$m++)
        {
        $definitiva=0;
        $definitiva=($i/4)+($j/4)+($k*3/10)+($l/20)+($m/20);
        if($i>=10)
          {
          $definitva+=0.5;
          }
         if($j>=10)
          {
          $definitva+=0.5;
          }
          if($k>=10)
          {
          $definitva++;
          }
          if($definitiva>17)//($definitiva>=8.5)&&($definitiva<9.5))
          {
echo "Has podido sacar " . $i . " , " . $j. " , " . $k . " en los parciales y ". $l ." , " . $m . " en los talleres y te daba ".$definitiva ."<br>";
          }
        }
      }
    }
  }
}


?>

[NachoF]

Nevermind.... i figured it out...definitiva was misspeled under the conditions to add 0.5 or 1