a person crosses a 720 m long street in 12 minutes . what is his speed in km per hour ?
"speed = 720 / ( 12 x 60 ) m / sec = 1 m / sec . converting m / sec to km / hr = 1 x ( 18 / 5 ) km / hr = 3.6 km / hr . answer : a"
divide(divide(720, const_1000), divide(multiply(12, const_60), const_3600))