4. (30 Marks) Earthworks is an excavation company which started its operations in the year 2008. The board of governors set the Minimum acceptable rate of return for the company at 12% after-tax. Due to the nature of their work, Earthworks own equipment which are in CCA class 8 (CCA rate = 20%). For the 5 years following its inception, Earthworks purchased 4 Machines, two of which they ended up selling. The record of their transactions is as summarized below: Transaction Dollar Value of transaction Tax Year 2008 2009 Purchase of Machine A Purchase of Machine B $70,000 $145,000 2010 Sale of Machine A $30,000 2010 Purchase of Machine C $90,000 2011 Sale of Machine B $55,000 2012 Purchase of Machine D $85,000