Calvin purchased a 40% partnership interest for $43,000 in February 2018. His share of partnership income in 2018 was $22,000, in 2019 was $25,000, and in 2020 was $12,000. He made no additional contributions to or withdrawals from the partnership. On December 18, 2020, Calvin sold his partnership interest for $103,000. What is his gain or loss on the sale of his partnership interest?