use strict;
use warnings;

my @ta = (q{a x}, q{b y}, q{c z});

my $key = q{b};
print qq{key = $key, value is @{[getValue($key)]}\n};

sub getValue
{
    my $key = shift;
    return
       map  { $_->[1] }
       grep { $_->[0] eq $key }
       map  { [ split ] }
       @ta;
}