T>..............[A]........F.............[B]

Train T is approaching tunnel AB.

Inside the tunnel is Felix The Cat located at point 3/8th
of the distance AB measured from the entrance A.

When the train whistles, Felix runs.

If Felix runs West, the train hits Felix exactly at the entrance A.

If Felix runs East, the train hits Felix exactly at the exit B.

If Felix's speed is 10 mph, what is the train's speed?

T>..............[A]........F.............[B]

AB = distance from A to B
TA = distance from the train to A
s = speed of the train

10 mph/s = 3AB/8TA = 5AB/8(TA+AB)

From the right equation, TA = (3/2)AB
Substituting into the left equation, s = 40 mph

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