Actually,  mam I have little bit doubt in subject selection process .I read an article (jee main eligible ctiteria) in which student should got 75% in following  subject..1 core subject , maths,physics,chemistry,and 1 additionl subject. I have 76% in case of subject pcm, hindi,English...But in case of pcm,English,computer  i  wil have only 73%

Yes, you have read that right. Have you chosen Hindi and computer both as your optional subjects? If it's so, then best of Hindi and Computer would be taken. You may consult your school teachers in this respect, I guess.  

From the information bulletin of JEE MAIN 2019, it seems they are considering only 3 subjects. PCM ONLY. That also may be the case. 

Ok that's niceBut what what percentage they wantI mean how much % should I have in pcm to qualify .... Is it also 75

Yes, that is minimum 75% in PCM.  

See Vaibhav, 12th percentage will be calculated as:1 compulsory subject -English3 electives - PHYSICS, CHEMISTRY, MATHS in                        your case. 1 any other language or additional subject in which you score higher,  which would be Hindi in your case.            So, no worries!            Hope, there is no confusion now. And I would still suggest you to consult your school principal in case of such doubts.  

Thanks a lot ....mam