You can follow the steps to calculate your marks in all semesters-

1. Find out the total marks of all the semesters and add them.

Semester 1+ semester 2 + semester 3 + semester 4+ semester 5 + semester 6.

2. Find out your total obtained marks in all semesters  out of total marks of all semesters.

3. Add them .

Marks obtained in-

(semester 1+ semester 2+semester 3+semester 4+semester 5+semester 6) .

4. Now , divide your total obtained marks by the total marks of all the semesters.                                 ( Step 3/ step 1).

5. Then multiply 100 with the number you got on step 4. And this is your required marks.

Hopes this helps.