Unearned rent represents two months rent received in advance from a tenant on December 1,2012.

Unearned Rent = $15,000 (Unadjusted Trial Balance)

What adjustments should I do?

HELP ME PLEASE!

Thanks!

Unearned rent account represents 2 months of rent received in advance on Dec 1, so assuming your trial balance was done on Dec 31 you need to account for one month of rent. So divide your Unearned Rent by 2 to get the amount of rent used for Dec.

Your journal entry will be:
Debit Rent Expense for the amount calculated above
Credit Unearned Rent for the same amount

This transfers one month of rent used from Unearned Rent to Rent Expense.