snell's answer to Silin's Primary 6 Maths Geometry Singapore question.
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W
dist. : 5d
time: t
speed: v
time t = 5d/v
Sam
dist. : 9d
time: t
speed: v+100
time t = 9d/(v+100)
at the same time t,
5d/v = 9d/(v+100)
5/v = 9/(v+100)
5v+500 = 9v
v = 125
Weili's speed is 125 m/min
...
dist. : 5d
time: t
speed: v
time t = 5d/v
Sam
dist. : 9d
time: t
speed: v+100
time t = 9d/(v+100)
at the same time t,
5d/v = 9d/(v+100)
5/v = 9/(v+100)
5v+500 = 9v
v = 125
Weili's speed is 125 m/min
...
Date Posted:
4 years ago
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