can someone please help me with this economic question

2 Maintenance costs for a new piece of mining equipment are expected to be $20,000 in the first year, rising by $2,500 per year thereafter. The machine has an expected life of 10 years and interest is 5% annually. To evaluate bids from outside firms fora maintenance contract you need to know the present value of these costs. What is this value? What is meant by the term cash flow? For the table below determine the yearly cash flows and the total cash flow. If a discounting rate of 8% is used what is the Net Present Value? Year Revenue Operating cost Capital costs Tax costs Project cash flow 2 170 3 200 -200 -100 4 230 -60 -50 5 260 -70 -60 6 290 _80 -70 3 A coal stripping company currently operates three dozers for reclamation work To reduce costs three alternatives are being considered for the future: rebuild the present equipment, purchase new dozers and employ a contractor. Details of the alternatives are given overleaf: No of units required Initial cost per unit Annual costs per unit Maintenance Labour Supplies Life Salvage value per unit Rebuild 3 $360,000 $140,000 $240,000 $58,000 8 years $0 Purchase 2 $920,000 $85,000 $160,000 $42,000 8 years $120,000 Contractor N/A so 8 years so If interest is 5% annually, which alternative should be selected?