The Malecs sold a painting on July 12, 2018 for $14,000. The Malecs had received the painting from Cals great uncle as a wedding present on June 25, 1980. Cals great uncle originally purchased the painting for $2,000 on January 1, 1968. The painting was valued at $25,000 on the date of the gift. No gift tax was due, or paid, on the gift.

How would i put this information onto a tax return?