Leases : calculate capital and interest repayments

[finance]

Hi - any help would be greatly appreciated.

We're leasing equipment at present from a supplier.
We have decided to finance the lease through a finance company.
We pay our finance company a fixed amount each month for the next 33 months.

My problem is that I have to calculate what proportion of the fixed amount is capital and what proportion of the fixed amount is interest for the next 33 months - and post the amounts to the general ledger.

I have reviewed the lease agreement from the finance company - there is no interest rate quoted on the agreement.
Is there a method to do this?

Any help would be greatly appreciated.

Thanks