If Theo took it, then statements 10 and 12 would be false, meaning he didn't take it.
Margaret didn't take it because otherwise, statements 13 and 14 would be false.
If statement 15 is true, then statements 8 and 9 would be false, which is impossible. Therefore, statement 15 is false, and statements 13 and 14 are true.
Added 1 minute later
Lilian didn't take it because if she did, then both her first and second statements would be false, which is impossible. This means Theo didn't do it either. As a result, her third statement is a lie.
Ничто не возникает из ничего и ничто не пропадает бесследно.
Если где-то чего-то убудет, то в другом месте добавится.
(Закон сохранения).