Answer:
December 31
Unearned Rent 7800 Dr
Rent Revenue 7800 Cr
Step-by-step explanation:
The rent received in advance for 5 months was $13000 and it was recorded as a debit to cash and a credit to unearned rent which is a liability. On 31 December, the rent for 3 months from October to December was earned and it should be recorded as a revenue. The entry would be to debit the unearned rent liability for 3 months worth of rent of $7800 and credit the rent revenue account by the same amount.