sub add { return $_[0] + $_[1]; }
sub subt { return $_[0] - $_[1]; }

sub dosth
{
    my ($func, $num0, $num1) = @_;
    return $func->($num0, $num1);
}

print dosth(\&add, 3, 2) . " " . dosth(\&subt, 3, 2); # desired output: 5 1

5 1