If supplies have a beginning balance of 1,245 and was debited for 2,860 for supplies purchased during the year. How do I journalize the adjusting entry required at the end of the year assuming the amount of supplies on hand is 1,349

you need to compute how much of supplies have been used.
Beginning Balance + purchases - Ending Balance(supplies on hand) = amount used.

the adjusting entry is:
Debit Supplies Expense for the amount used
Credit Supplies for the amount used.