SOLUTION: Sarah takes 40 minutes to walk to her office and only 12 min if she rides her bike. Her speed when walking is 7 miles per hour less than her speed when riding her bike. (assume she

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Question 564822: Sarah takes 40 minutes to walk to her office and only 12 min if she rides her bike. Her speed when walking is 7 miles per hour less than her speed when riding her bike. (assume she takes the same path to her office). What is the distance to her office.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Sarah takes 40 minutes to walk to her office and only 12 min if she rides her bike.
Her speed when walking is 7 miles per hour less than her speed when riding her bike. (assume she takes the same path to her office).
What is the distance to her office.
:
Let s = his walking speed
then
(s+7) = his biking speed
:
Write a distance equation; dist = speed * time
We need the time in hrs
:
40%2F60s = 12%2F60(s+7)
Reduce the fractions
2%2F3s = 1%2F5(s+7)
Multiply by 15 to clear the denominators
5(2s) = 3(s+7)
10s = 3s + 21
10s - 3s = 21
7s = 21
s = 21/7
s = 3 mph is his walking speed
:
Find the distance
2%2F3(3) = 2 miles
Check the distance
1%2F5(3+7) = 2 miles also