Hi

my approach, as I don't know which rules are followed by the names 'orange 5':

use strict;
use warnings;
use 5.010;

my @a = ('apple 2', 'orange 5', 'pear 3');
my @b = qw/apple apple apple orange orange pear apple orange orange/;

my %a;
my @c;

foreach my $fruit (@b) {
    if(exists $a{$fruit}) {
        push @c, $a{$fruit};
        next;
    }
    my ($hit) = grep { $_ =~ /$fruit/ } @a;
    push @c, $hit;
    $a{$fruit} = $hit;
}
say join "\n", @c;
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Best regards
McA