Problema Solution

a train travels 110 km in the same time that a plane covers 385 km. if the speed of the plane is 20 km per hour less than 4 times the speed of the train, find both speeds

Answer provided by our tutors

Let


x = the speed of the train

y = the speed of the plane


the time that the train travels 110 km = the time that plane travels 385 km


since the formula for the speed is v = s/t where v d = distance, t = time


then for the time we can write t = s/v thus


110 / x = 385 / y


the speed of the plane is 20 km per hour less than 4 times the speed of the train


y = 4*x - 20


By solving the system of equations


110 / x = 385 / y

y = 4*x - 20


we find


x = 40 km/hour


y = 140 km/hour


The speed of the train is 40 km/hour and the speed of the plane is 140 km/hour.