Question 214936
A train leaves Kansas City, Kansas and travels north at 85 km per hour. Another train leaves at the same time and travels south at 95 km per hour. How long will it take before they are 315 km apart?


Step 1.  Distance = Speed *  Time


Step 2.  Let x be the time when the two trains are 315 km apart.


Step 3.  Let 85x be the distance traveled by the train going north.


Step 4.  Let 95x be the distance traveled by the train doing south.


Step 5.  85x+95x=315   Adding Steps 3 and 4  is the total distance when the trains are 315 km apart.


{{{180x=315}}}


{{{180x/180=315/180}}}


{{{x=1.75}}} hours or 1 hour and 45 minutes where 0.75 hour*60 minutes/hour=45 minutes.


Step 6.  ANSWER.  It will take 1 hour and 45 minutes for the trains to be 315 km apart.


I hope the above steps were helpful.


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Good luck in your studies!


Respectfully,
Dr J