A train leaves a station and travels north at a speed of 45 km/h. Two hours later, a second train leaves on a parallel track and travels north at 75 km/h. How far from the station will they meet?

The trains will meet 225km north from the station.

Explanation:

First, we need the equation of position of the two trains. Since they have constant velocities, these equations are:

Where is the time the first train is traveling before the second train levaes the station. When the trains meet, . If we solve for t in the equations above, we have:

Matching these equations and solving for x, we obtain:

In words, the trains will meet 225km north from the station.

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