A person travelled from his house to office at 30km/hr and office to house at 15km/hr. Then find the average speed? Choose the correct choice:  A) 15km/hr  B) 20km/hr  C) 32km/hr  D) 24km/hr  E) 25km/hr
Average speed = (2*30*15)/(30+15)= 
<gadget id="calculator">(2*30*15)/(30+15)</gadget>
<output>20</output>
20km/hr   Answer is 20km/hr
<result>B</result>
A person travelled from his house to office at 30km/hr and office to house at 15km/hr. Then find the average speed?