please explain what compound interest factors were used and why. Thank you

7. A company is trying to decide between fixing the floors in a building or rebuilding the floors. If the floor is fixed, the job will require 350 cubic metres of flooring at a cost of $40 per cubic metre. Maintenance of the floor is expected to be $2000/year and will last only two years before needing to be fixed again. The company could redo the entire floor in the building for $40,000, which would last for 6 years and require maintenance at $1000 for Years 4 through 6 . No matter what alternative it selects, the company will move to a new building in 6 years. If the company's MARR is 12% per year, what alternative should it select using rate-of-return analysis