The table below gives the annual sales in millions of dollars of a product year 1998 1999 2000 2001 2002 2003 2004 2005 2006 sales 277 297 313 309 297 277 213 249 309 Determining the average rate of change of sales is important It tells whether sales are increasin decreasing over a time period and at what rate a What was the average rate of change of annual sales between 2003 and 2004 millions of dollars year b What was the average rate of change of annual sales between 2003 and 2005 millions of dollars year