CBSE — Why CBSE has given me intolerable marks this year in my 12 boards?

On 30 July 2021 our 12 boards result have been declared .CBSE used a criteria 30:30:40 for giving marks .I m not satisficed with my result of any subject .Because I got 90% in 10 class boards and in 11 class I got 75% and in 12 pre boards I got 92% .so how can I get 73% in my boards. CBSE has done a fraud to many students this year. Most of the students who got 40% in their 11 class and 70 to 80% in their 10 boards and got 70 to 80 % in their class 12 pre boards have gotten 90 to 95 % marks in CBSE this year . How can be this possible .we have scored so much in our 11, 12, 10 but then also we have get such intolerable marls. In Practical also I got 19/20, 18/20, 27/30, 28/30 and 29/30 . Then how can i get 73 % marks in my class 12 boards.