Question 1110223
A child is running on a moving sidewalk in an airport. When she runs against the sidewalk's motion, she travels 50ft in 10 seconds. 
When she runs with the sidewalk's motion, she travels 91ft in 13 seconds.
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What is the rate of the child on a still sidewalk and what is the rate of the moving sidewalk?
Find the 2 speeds, with and against the motion.
Her speed is the average of the 2.
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The s/w speed is the difference between her speed and either of the other 2.