A person travelled from his house to office at 30km/hr and office to house at 10km/hr. Then find the average speed?  Pick:
A) 15km/hr B) 20km/hr C) 32km/hr D) 24km/hr E) 25km/hr
15km/hrverage speed = (2*30*10)/(30+10)= 
<gadget id="calculator">(2*30*10)/(30+10)</gadget>
<output>15</output>
15km/hr   15km/hrnswer is 15km/hr
<result>A</result>
A person travelled from his house to office at 30km/hr and office to house at 10km/hr. Then find the average speed?