please solve part a and b people repeatedly getting this question wrong! after I paid for professional answers

can someone please answer this question and show your work? the last person was wrong and didn't show any work either A road can be paved with either Asphalt or Concrete. Concreate costs $20,000/Km and last 20 years. Assume the annual maintenance costs are $700 for Concrete and $1,000 for Asphalt per kilometer per year. Use an interest rate of 15% per year. Explain in detail your set up, Formula, Calculation, and recommendation a) What is the maximum that should be spent for Asphalt if it lasts only 10 years? b) Assume the asphalt road costs $8500 per kilometer. How long must it last to be the preferred alternative? c) Summarize your Conclusions of tow on the environmental computation of Asphalt versus Concrete