When I was at school many decades ago, I would have read that as 'two-x-plus-one over four'. The hyphens are meant to suggest that I would have read these words as one unit. It would have been clear that I was not saying 'two x plus one-over-four'.
A more formal reading would be [the] quantity two-x-plus-one over four. The term quantity primes the interlocutor to listen for a logical place to mentally insert the closing parenthesis (bracket).