SOLUTION: Two trains leave at the same point. One train leaves at noon at 50mph. The other train leaves 2 hours later at 90mph. At what time will the second train catch the first train?

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Question 201114: Two trains leave at the same point. One train leaves at noon at 50mph. The other train leaves 2 hours later at 90mph. At what time will the second train catch the first train?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Assume I have a stopwatch. I'll start
it when the 2nd train leaves at 2 PM.
How far has the 1st train gone in
2 hours?
50%2A2+=+100 miles
When I start the stopwatch, both trains
will travel for t hrs
If the 2nd train's distance is d,
the 1st train's distance is d+-+100
Now I can write an equation for each one
2nd train:
d+=+90t
1st train:
d+-+100+=+50t
Substituting:
90t+-+100+=+50t
40t+=+100
t+=+2.5
This is the elapsed time starting at 2 PM
The 2nd train catches the 1st train at 4:30 PM