The newspaper in Haventown had a circulation of 80,000 papers in the year 2000. In 2010, the circulation was 50,000. With x=0 representing the year 2000, the graph below models this scenario. A coordinate plane showing Newspaper Circulation, Years Since 2000 on the x-axis and Circulation on the y-axis. A line starting at (0, 80,000), passing through a point at (10, 50,000) and ending at (18, 25,000).

What number will complete the point-slope equation that models this scenario?