With 42 marks in AP EAMCET and 81% in CBSE Class 12 boards, your expected rank may fall in the 30,000 to 40,000 range. The AP EAMCET ranking system gives 75% weightage to EAMCET marks and 25% to board scores. Marks between 40-49 typically result in ranks above 30,000, depending on the competition and normalization process. To get a more precise estimate, you can use rank predictor tools available online.

For more details you can visit the link given below:

https://engineering.careers360.com/articles/ap-eamcet-marks-vs-rank