Maintenance cost for a small bridge expected to last for 60 years is estimated to be Php1,000 each for the first 5 years, followed by a Php10,000 expenditure in the 15th year and Php10,000 in the 30th...

Maintenance cost for a small bridge expected to last for 60 years is estimated to be Php1,000 each for the first 5 years, followed by a Php10,000 expenditure in the 15th year and Php10,000 in the 30th year. If interest is 10% per year, what is the equivalent uniform annual cost over the 60 year period?