Am I eligible to apply for NDA examination after having commerce mathematics subject in 12th grade

Yes you can apply for NDA examination after having commerce mathematics subject in 12th grade. you can apply for army wing of National Defence Academy

National Defence Academy (NDA) examination organized by union public service commission to join Army wings..

Eligibility:
For Army wing of National Defence Academy :-
12th Class pass of the 10+2 pattern of School Education or equivalent examination conducted by a State Education Board or a University.

For Naval Wings of National Defence Academy
You should be 10+2 passed with physics and mathematics subjects.

Age limit
16 ½ to 19 Years

Sex:
Only unmarried male candidates are eligible.

Vision Standards for Naval Candidates:
Uncorrected without glass 6/6
Corrected with glass 6/6
Limits of Myopia -0.75
Limits of Hypermetropia +1.5
Limits of Colour Perception I
Binocular Vision III