Teaching Textbooks

In order to prepare for possible re-entry to the classroom, I have begun by reviewing Algebra 2 in order to revitalize skills I haven't practiced for years.

In one of the lessons I came across this item.

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PROBLEM:

A man is 3/8 of the way walking across a railroad trestle when he hears a train approaching at 60 mi/hr. If he runs to either end of the bridge, he can just make it to safety as the train passes. How fast does he have to run?

SOLUTION:

If he runs back to the near end, he runs 3/8 of a bridge and gets out of the way as the train begins crossing the trestle.

If he runs to the far end, he runs an additional 3/8 of the bridge and is 6/8...