số hữu tỉ trg TA là j

assistant In the context of mathematical expressions, "trg TA" seems to be an abbreviation for "trong tập hợp A" (in set A), and "j" typically represents a specific element in that set. However, without more information, it's challenging to provide a precise answer. If you're asking for a translation or clarification, could you provide more context or details about the expression "số hữu tỉ trg TA là j"?