The changes in Toyota Prius U.S. sales (in thousands of cars) from one year to the next are shown in Table 23.
Table 23
Changes in Toyota Prius U.S. Sales
Changes in Sales
Years (thousands of cars)
2006–2007 …………………….. 74
2007–2008 …………………….. -23
2008–2009 …………………….. -19
2009–2010 …………………….. 1
2010–2011 …………………….. -13
2011–2012 …………………….. 19
2012–2013 …………………….. -2
a. If 107 thousand cars were sold in 2006, what were the sales in 2013?
b. During which period(s) were sales increasing?
c. During which period(s) were sales decreasing?