Q#1:
For the tractor retired after 7 years:

	Capital Recovery = ($24,000-$8,000)(A/P,8%,7)+8000*0.08 = $3,713
	Annual maintenance= $2,000

	So total annual cost = $5,713

For the tractor retired after 10 years:

	Capital Recovery = ($24,000-$4,500)(A/P,8%,10)+4,500*0.08 = $3,265

	Note after the 7th year the maintenance cost becomes $5,000.
        So we must find the equibvalent uniform annual maintenance.
        We will assume that there is uniform $2,000 for ten years and
        there is extra $2000 for the last three years.
        So equivalent uniform amount is:

	Equivalent uniform annual maintenance
        = $2,000+ $2,000 *(F/A,8,3)*(A/F,8,10)
        = $2,448

        So total annual cost = $5,714


Q#2:
Let X denote the number of days per year that the facility will be in use.
So the annual cost of owning the facility is:

	Capital Recovery
        = (24,000-1,800)(A/P,15%,4)+1,800*0.15 = $8046,66
	Fixed Cost
        = $9,200
	Operating Cost
        = $120X

        Total Cost = $17,246.66 + 120X

	The total cost of renting the facility is $225X

        So the break-even point can be found as follows:

	$17,246.66 + 120X = $225X

	So, we can find that X= 17,246.66/105 = 164.25 days
                                               (165 days)