Trading activity-Rule 6(3)a of Cenvat credit rules

Rs.1 cr. x Rs.40/Rs.50.  Rs.40 is the value of taxable services. Rs.50 = Rs.40 + (Rs.60-Rs.50). Actually preceding years figures can be adopted for the monthly apportionment. Then do adjument on the basis of  current year's figure after the year end.

Thanks for your answer sir. I still have a doubt on this. In the formula prescribed under rule, the numerator should be the exempted turnover. Whereas in your answer, you have taken taxable turnover as the numerator. Kindly clarify.

I was working out the admissible credit and not the reversible credit.