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Speed P6 Q
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TOPIC: Speed P6 Q
#4009
Speed P6 Q 1 Year, 6 Months ago Karma: 0
Tom left Town A for Town B at 11am. Jerry left Town B for Town A at 4 pm. At 7pm, Tom reached Town B but Jerry was still 240km from Town A. Both had travelled at constant speeds but Jerry was 20km/h faster than Tom. What is the distance between Town A and Town B?

Can't figure it out with so many unknown. Help!
Chua
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#4011
Re: Speed P6 Q 1 Year, 6 Months ago Karma: 0
Tom
Time -- 8 hours
Distance - D km
Speed -- S = D / 8 .... (1)

Jerry
Time -- 3 hours
Distance -- (D - 240) km
Speed -- (S+20) = (D - 240)/3 ... (2)

Substituting (1)into (2),

D / 8 + 20 = (D - 240) / 3
3D + 480 = 8D - 1,920
5D = 2,400
D = 480

Distance between Town A and Town B = 480 km.
Tay CK
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