When is implementation of a product backlog item considered complete?

Required prepare the necessary adjusting entries in the general journal as of december 31, assuming the following: on september 1, the company entered into a prepaid equipment maintenance contract. birch company paid $3,400 to cover maintenance service for six months, beginning september 1. the payment was debited to prepaid maintenance. supplies on hand at december 31 are $3,900. unearned commission fees at december 31 are $7,000. commission fees earned but not yet billed at december 31 are $3,500. (note: debit fees receivable.) birch company's lease calls for rent of $1,600 per month payable on the first of each month, plus an annual amount equal to 1% of annual commissions earned. this additional rent is payable on january 10 of the following year. (note: be sure to use the adjusted amount of commissions earned in computing the additional rent.)