Perhaps you meant to code you solution like this:
in reply to Printing set characters from offset.
my $line = ' j1000010017 6790194100109201301092013THIS TO BE PRINTED
+M PW09-3PY248005BIK00 ';
say substr( $line, 38, 20);
say substr( $line, 68, 3);
THIS TO BE PRINTED
Explanation: perldoc -f substr.
Because you didn't RTFM, you owe apologies to all those electrons which were inconvenienced by the creation of this post.