Answer:
- 42 mph
- 126 mph
Explanation:
It takes 2 hours for the second train to catch the first, so the first must have had a head start of (2 h)(84 mi/h) = 168 miles.
The first train achieved that head start in 4 hours, so its speed was ...
(168 mi)/(4 h) = 42 mi/h
The second train was 84 mi/h faster so its speed was ...
42 mi/h + 84 mi/h = 126 mi/h
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The two trains met at a distance of 252 miles from Boston.