SOLUTION: Joe drove 210km at 70km/h and then another 210 km at 105km/h. It took Bill the same length of time to drive the entire 420km at constant speed. What was Bill's speed?

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Question 212372: Joe drove 210km at 70km/h and then another 210 km at 105km/h. It took Bill the same length of time to drive the entire 420km at constant speed. What was Bill's speed?
Answer by HyperBrain(694) About Me  (Show Source):
You can put this solution on YOUR website!
time=distance/speed.
---
So, the total time it took for Joe to drive is:
t=%28210%2F70%29%2B%28210%2F105%29=3%2B2=5hr
---
speed=distance/time
=-=
So, Bill's speed is:
v=420%2F5=84km/hr