Conversation so far:
What charities did philanthropist Doris Duke sponsor?
Doris Duke was active in preserving more than 80 historic buildings in Newport, Rhode Island.
Which buildings did Doris Duke help restore?
Historic properties include Rough Point, Samuel Whitehorne House, Prescott Farm, the Buloid-Perry House, the King's Arms Tavern, the Baptist Meetinghouse, and the Cotton House.

Question: How much did she pay for the restoration of these buildings?
Self-contained rewrite: How much did Doris Duke pay for the restoration of historical buildings?