Concept:Find the net displacement using East-West and North-South directions.Explanation:Start at (0,0).After 7 km East: position (7,0).After 12 km South: position (7,−12).After 7 km West: position (0,−12).Now he faces West, so his left is South.After 10 km South: position (0,−22).His net East-West displacement is 7−7=0.His net South displacement is 12+10=22 km.So he is 22 km South of the starting point.
