Problema Solution
two trains start from the same station and run in opposite directions at an average rate of 64 km/hr and 86 km/hr,respectively. in how many hours will they be 225 km apart.
Answer provided by our tutors
Let
x = 64 km/h the speed of the first train
y = 86 km/h the speed of the second train
t = the time they need to travel
d = 225 km the distance between the trains in t hours
By definition speed = the distance passed / time needed thus the distance = speed * time.
That is
x*t + y *t = 5 (the sum of the distance that the first (x*t) and the second (y*t) train will pass equals the total distance)
64*t + 86*t = 225
150*t = 225
t = 225/150
t = 25/6
t = 4 1/6 hours = 4 hours 10 min (since 1 hour = 60 min)
In 4 hours 10 min the trains will be 225 km apart.