As per given line graph, we can see that the
Sales in the year 2005 = 10 billion $
Sales in the year 2006 = 6 billion $
Sales in the year 2007 = 6 billion $
Sales in the year 2008 = 5 billion $
∴ Required total sales = Sum of all sales from 2005 to 2008
Required total sales = $ (10 + 6 + 6 + 5) billion= $ 27 billion
