SOLUTION: A rider on horseback travels from point Narnia to Archenland at an average speed of 20 miles/hour and returns at an average of 18 miles/hour. If the round trip takes 8 hours, find

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Question 1108263: A rider on horseback travels from point Narnia to Archenland at an average speed of 20 miles/hour and returns at an average of 18 miles/hour. If the round trip takes 8 hours, find the distance between Narnia and Archenland.
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
                 SPEED           TIME              DISTANCE

TO                 20            d%2F20           d

RETURN             18            d%2F18           d

TOTAL                              8

d%281%2F20%2B1%2F80%29=8

Answer by ikleyn(52887) About Me  (Show Source):
You can put this solution on YOUR website!
.
Your "time" equation to find the distance d is


d%2F20 + d%2F18 = 8   hours.


Each term (each ratio) in the left side is the time to cover the one way distance.


Multiplying both sides by 180 (common denominator) you get


9d + 10d = 8*180


19d = 1440  ====>  d = 1440%2F19 = 75.789 miles (approx.)
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Be aware : The basic equation by @josgarithmetic is written incorrectly !