Question 1015965
Local: (35mph)(1.5hr)=52.5 mi
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When the express train starts, the local is 52.5 miles ahead.
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The express catches up (56mph-35mph=) 21 miles per hour.
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52.5 miles/ 21 mi/hr=2.5 hours
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ANSWER: The express train will catch the local 2.5 hours after 
the express train starts.
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