My variables are getting mixed up --RESOLVED (I'm an idiot)

If I run the the code below, I get an unexpected result.
I would expect
  Camping
  Nation
  First
  33
  32
  31
  32
  32
  31
Instead I get:---and I don't understand why.  Anyone able to help?
  Camping
  Camping
  Camping
  33
  32
  31
  32
  31
  30

--------------------------------- code snippet below ------------------------------

$SixPM_form = "Camping";
$SevenPM_form = "Nation";
$EightPM_form = "First";
$CampingSixPM = "33";
$CampingSevenPM = "32";
$CampingEightPM = "31";

          
if ($SixPM_form = "Camping")
    {
    $UpdateCampingSixPM = ($CampingSixPM - 1);
    }
   
if ($SevenPM_form = "Camping")
    {$UpdateCampingSevenPM = ($CampingSevenPM - 1);
    }
   
if ($EightPM_form = "Camping")
    {
    $UpdateCampingEightPM = ($CampingEightPM - 1);
    }


echo $SixPM_form;
echo $SevenPM_form;
echo $EightPM_form;
echo $CampingSixPM;
echo $CampingSevenPM;
echo $CampingEightPM;
echo $UpdateCampingSixPM;
echo $UpdateCampingSevenPM;
echo $UpdateCampingEightPM;