a person crosses a 1800 m long street in 12 minutes . what is his speed in km per hour ?
"speed = 1800 / ( 12 x 60 ) m / sec = 2.5 m / sec . converting m / sec to km / hr = 2.5 x ( 18 / 5 ) km / hr = 9 km / hr . answer : e"
divide(divide(1800, const_1000), divide(multiply(12, const_60), const_3600))