Three cars, A, B and C, set off from the same place at the same time and chased the cyclist in front along the same highway. The speed of car A is 54 kilometers per hour, and that of car B is 48 kilometers per hour. Car A fails to catch up with the cyclist in 6 hours, car B catches up with the cyclist in 7 hours, and car C 14 hours catches up with the cyclist. Q: How many kilometers per hour is the C train?

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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