I am needing to see all the hand written work on this as we as the cashflow diagram please.

Annual maintenance cost for a particular section of highway pavement are $2,500. The placement of a new surface would reduce the annual maintenance cost to $500 per year for the first three years and to $1,000 per year for the next 7 years. After 10 years the annual maintenance would again be $2,500. If maintenance costs are the only saving, what investment can be justified for the new surface? Assume interest at 5%.