SOLUTION: Word problem: David gets to work in 20 minutes when he drives his car. Riding his bike (by the same route) takes him 45 minutes. His average driving speed is 4.5mph greater than

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Question 1160090: Word problem: David gets to work in 20 minutes when he drives his car. Riding his bike (by the same route) takes him 45 minutes. His average driving speed is 4.5mph greater than his average speed on his bike. How far does he travel to work?
I have an answer key, but can't figure out how to get the right answer. I've tried several equations to no avail.
Thanks,
Daniel
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
           SPEED             TIMEin hours    DISTANCE

BIKE         r               3%2F4             d

CAR          r+4.5           1%2F3             d

The same distance whichever vehicle used.

%28r%29%283%2F4%29=d=%28r%2B4.5%29%281%2F3%29

%28r%29%283%2F4%29=%28r%2B4.5%29%281%2F3%29
Simplify and solve this for r.

-----

3.6 mph for bicycle

Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
.

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