A person travelled from his house to office at 30km/hr and office to house at 70km/hr. Then find the average speed?
Choose the correct choice from the following answers.
A) 30km/hr  B) 40km/hr  C) 42km/hr  D) 50km/hr  E) 62km/hr
Average speed = (2*30*70)/(30+70)= 
<gadget id="calculator">(2*30*70)/(30+70)</gadget>
<output>42</output>
42km/hr
Answer is 42km/hr
<result>C</result>
A person travelled from his house to office at 30km/hr and office to house at 70km/hr. Then find the average speed?