Hello,

Don't worry. To be eligible for JEE Main, you have to make sure to get minimum 75% score in class 12.

Moreover, to prepare for the exam:

As you said you are bad in Intermediate syllabus, start with thoroughly revising your NCERT. You should also solve the Textual Exercises.

Then you can start solving the previous papers and learning the concepts that you didn't know earlier.

To prepare for JEE Advanced, you have to refer reference books a lot and go deep into the concepts.

To make your task easier, you can try our JEE Main Knockout Package by Careers360:

https://learn.careers360.com/knockout-jee-main-april/

Hope this helps.

Thanks.