algebra

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The boys were 1/
4 of the way across the bridge when they heard the sound of a train whistle. The train
coming from behind them was moving at a speed of 45 mph. The boys immediately thought that they could
turn around and run towards the near end of the bridge, and get to the end at the same time the train did. But,
they also knew that they could run to the far end of the bridge and get to the end at the same time the train
did.
• How fast were the boys running assuming they were 1/
4 of the way across the bridge?
• Suppose the boys were 2/
5 of the way across … how fast do they run?
• Suppose the boys were 1/
3 of the way across … how fast do they run?
• Suppose the boys were
3/
8 of the way across … how fast do they run?

• Write a generalization to solve this problem for any fractional amount.

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