assets depreciation

Hi

My requirement is that suppose one asset is aqcuired in APril, then epr rate is 10%, another in May then rate will be 11%

e.g.

Asset 1 @ Rs.10000 Rate will be 10 % for 12 months ( acquired in April )

Asset 2 @ Rs.15000 Rate will be 15% for 11 months ( Acquired in May )

How to achive this

Pushkaraj