A port authority intends to build a bridge and has two main options. a high level reinforced concrete bridge and a low level-steel bridge. the high level bridgehas an initial construction cost of 40 million, with maintenance costs estimated at 40,000 per annum. its asphalt road surface would have to be relaid every 10 years at a cost each time of 75,000. the low-level steel bridge and ancillary works are estimated at 35 million with maintenance costs estimated at 30,000 per annum. its road must be relaid every 10 years at a cost of 45,000 each time. use present worth analysis to compare the two options over a period of 50 years based on a rate of interest of 5% per annum.