Problema Solution

A train travels 100km in the same time that a plane covers 450km. If the speed of the plane is 20km per hour less than 5 times the speed of the train find both speeds

Answer provided by our tutors

let


v1 = the speed of the plane

d1 = 450 km the distance the plane travels

v2 = the speed of the train

d2 = 100 km the distance the train travels


the speed of the plane is 20km per hour less than 5 times the speed of the train


v1 = 5v2 - 20


since speed = distance/time => time distance/speed


v1/d1 = v2/d2


v1d2 = v2d1


100v1 = 450v2


by solving the system of equations


v1 = 5v2 - 20

100v1 = 450v2


we find


v1 = 180 km/h is the speed of the plane


v2 = 40 km/h is the speed of the train


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