The average number of electronic items sold by a trader in 2004, 2005, 2006 and 2007 is 18950 and that sold in 2005, 2006, 2007 and 2008 is 21725. If the number of items sold in 2008 is 12750, then the number of items sold in 2004 is:

1650

Sum of number of items sold from 2004 till 2007 = 4 × 18950 = 75800

Sum of number of items sold from 2005 till 2008 = 4 × 21725 = 86900

Number of item sold from 2005 to 2007 = 86900 - 12750 = 74150

Number of item sold in 2004 = 75800 - 74150 = 1650