SOLUTION: Mary lives 6 miles from the mall. She rides her bike to the mall. She rides 4 miles before she meets her friend. They drop off the bike and run together. It then takes them the sam

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Question 186928: Mary lives 6 miles from the mall. She rides her bike to the mall. She rides 4 miles before she meets her friend. They drop off the bike and run together. It then takes them the same amount of time to run the rest of the way to the makk as it took Mary to ride the bike for the first 4 miles. She can bike 8 mph faster than she runs. How fast can she bike?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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Mary lives 6 miles from the mall. She rides her bike to the mall.
She rides 4 miles before she meets her friend.
They drop off the bike and run together.
It then takes them the same amount of time to run the rest of the way to the
mall as it took Mary to ride the bike for the first 4 miles.
She can bike 8 mph faster than she runs. How fast can she bike?
:
Let s = M's bike speed
then
(s-8) = M's running speed
:
Write time equation: time = dist%2Fspeed
:
Bike time = Running time
4%2Fs = 2%2F%28s-8%29
:
Cross multiply:
4(s-8) = 2s
4s - 32 = 2s
4s - 2s = 32
2s = 32
s = 32%2F2
s = 16 mph is the bike speed
:
:
Check solution, find the times of biking and running:
4/16 = .25 hr
2/8 = .25 hr