The cost of one kilometre of a highway increased from $4.3 million (mln) in 2007 to $7.9 million in 2015. At the same me the CPI rose from 108.1 in 2007 to 129.4 in 2015. Assuming that the inaon rate per year is unknown, what is the difference between the 2007 and 2015 costs of one kilometre of the highway expressed in real dollars? answer: $2.3 mln