Win8 Strawberry 5.30.3.1 (64)  Fri 09/25/2020 23:09:19
C:\@Work\Perl\monks
>perl
my $kards = -99;
my $bad='$card$card';
my $card='K';
eval {print "eval is testing for $card in $bad \n";
       $kards = $bad =~ tr/$card//; # tried also tr/$card/$card/; same bad result.
      };
print "1: Num of $card in $bad = $kards \n";
$king = $bad =~ tr/$card//;
print "2: Num of K in $bad is = $king \n";

__END__
eval is testing for K in $card$card
1: Num of K in $card$card = 10
2: Num of K in $card$card is = 10