Solve for x
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The problem looked simple.
A train headed east at 25,
another headed west at 45.
When did they meet?

But what if the tracks weren't parallel?
What if they were on a hill?
What if one saw a moose and had to slow down?
What if the conductor was on a tight schedule?
What if they were on the same track?
What if they were in a valley?
What if one saw a bear and had to speed up?
What if the conductor desperately needed to kill time?

I'm afraid, mister
that I can't solve this problem.