Ten years ago, Art purchased land for $60,000 and immediately titled it in the names of Art and Ban, joint tenants with right of survivorship. Ban paid no consideration. In 2019, Art died and was survived by Ban, his brother. The land's value had appreciated to $300,000. 

a. What was the amount of the inclusion in Art's gross estate? 

b. Assume Ban died (instead of Art). What amount would have been included in Bares gross estate? 

c. Assume that An died in January 2019 and Ban died in November 2019, when the land was worth $320,000. What amount was included in Ban's gross estate?