SOLUTION: The train traveled at s meters per minute for d meters and arrived 9 minutes late to its destination. How fast should the train have travled to make it to its destination on time?

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Question 1151340: The train traveled at s meters per minute for d meters and arrived 9 minutes late to its destination. How fast should the train have travled to make it to its destination on time?
Thank you!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = the time in minutes for
the train to arrive on time
Let +r+ = speed of train in order to arrive on time
-------------------------------------------
+d+=+s%2A%28+t+%2B+9+%29+
+d+=+s%2At+%2B+9s+
+s%2At+=+d+-+9s+
+t+=+%28+d+-+9s+%29%2Fs+
I can say:
+d+=+r%2A%28+d+-+9s+%29%2Fs+
+r+=+d%2As+%2F+%28%28+d+-+9%2As+%29%29+
+r+=+d+%2F+%28%28+d%2Fs+-+9+%29%29+ answer
------------------------------------
check:
The new time is +d%2Fs+-+9+
( to arrive on time )
The is 9 min less than the previous time as it should be.