Starting July $1,$ Year $7,$ Ironman begins selling extended warranties for Ironman II units whose original warranties have expired, charging $$600$ for an additional two years of service, with expected costs of $$500$ over the period. From July $1$ to December $31,$ Year $7,$ the company sells $80$ extended warranties and incurs $$16,000$ in repairs related to these warranties. Prepare journal entries for sales of the extended warranty and actual warranty costs incurred. Also prepare the related adjusting journal entry at year$-$end.