trading it in at the end of year j (where year 0 is now) 0 10 21 12 minimize the total cost for the tractors over 3 years. (10 points) oulo The problem is to determine at what times (if any) the tractor should be replaced to4 trading it in at the end of year j (where year 0 is now). j 1 2 3 0 8 18 31 i 1 10 21 2 12 The problem is to determine at what times (if any) the tractor should be replaced to minimize the total cost for the tractors over 3 years. (10 points)