I got 49 and 70 in 10th and 12th respectively and 7.5 out 10 CGPA in grads. How much do I have to score to get into FMS Delhi?

According to the eligibility criteria, you must have completed a Bachelor's Degree with at least 50% marks at the graduation level (SC/ST: Passing marks; OBC/PWD/CW: 45% weightage as per university rules) or equivalent CGPA.

It doesn’t mention anything about the 10th and 12th marks for being eligible for admission, but there is a weightage of 

• Marks obtained in Class X - 10% weightage (60% and above but less than 75%: 5%, 75% and above: 10%)
• Marks obtained in Class XII - 10% (60% and above but less than 75%: 5%, 75% and above 10%)

So, you will need to perform really well in the SOP, Extempore, and PI along with the CAT exam to stand a chance for admission.