Solution: Suppose the speed of a cyclist is one kilometer per hour.
(54-a)×6=(48-a)×7
324-6a=336-7a
A =12km/h
Initial distance difference between cyclist and A, B and C = (54- 12) × 6 = 252km.
Then the speed c = 252/14+12 =18+12 = 30km/h.
Arithmetic:
B 6 hours driving 48×6 = 288 kilometers.
At this time, 1 hour later, B caught up with the cyclist, who was at 54×6=324 km.
Distance difference = 324-288 = 36 kilometers
Then the speed of the cyclist = 48-36/(7-6) = 48-36 =12 km/h.
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