my $string = <<EOT;
<span class="style">28.56</span><span class="style">-1.22</span><span class="style">-4.1</span><span class="style">04/02</span>
EOT

my $decimal = qr/[-+]?(?:\d+\.?\d*|\d*\.\d+)/;

my ( $frst, $scnd ) = ( $string =~ /($decimal).*?($decimal)/ );

print "$frst, $scnd\n";