Heyy 

The aggregate for securing a seat is 45% and a 50% is required in the subject of concern making an individual eligible for a honours seat under Delhi Unniversity, therefore merits are determined on the basis of one language and 3 best subjects and students who have cleared an intermeditae exam from an Indian University or Board. So depending on the basic eligibility a 70 should be enough to pass the exam. Hope that was helpful