arodriguez1982
contestada

A child is running on a moving sidewalk in an airport. When he runs against the sidewalk's motion, he travels
84ft
in
14
seconds. When he runs with the sidewalk's motion, he travels
70ft
in
7
seconds. What is the rate of the child on a still sidewalk and what is the rate of the moving sidewalk?

Respuesta :

rate=distance/time
Rate of the child when he runs aginst the side walk´s motion
rate=84 ft/14 s=6 ft/s


Rate of the child when he runs with the sidewalk´s motion.
rate=70 ft/7s=10 ft/s

rate of the moving sidewalk=x
rate of the child=y

We can suggest this system or equations_
y+x=10
y-x=6

We can solve this system of equations by reduction method. 

y+x=10
y-x=6
---------------
2y=16        ⇒y=16/2=8

  y+x=10
-(y-x=6)
----------------
     2x=4            ⇒x=4/2=2

Answer: The rate of the child would be 8 ft/s and the rate of the sidewalk´s motion would be 2 ft/s. 


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