Question 1069683
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<pre>
Time they travel before they cross each other is  {{{500/(20+30)}}} = 10 hours.


During 10 hours the first train covers  10*20 = 200 km.


<U>Answer</U>.  200 km.
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The tutor "MathTherapy" wrote his own solution.
Probably, he tried to prove that I made a mistake in my solution.


But instead, he made a mistake in his own solution.


Below I re-wrote his solution with my correction. It gives the same result/answer as my original solution.
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<pre>With D being the distance from X where they cross, we get the following TIME equation: {{{D/20 = (500 - D)/30}}}
30D = 20(500 - D) ------- Cross-multiplying
30D = 10,000 - 20D
30D + 20D = 10,000
50D = 10,000
D, or distance form X where they cross = {{{highlight_green(matrix(1,4, "10,000"/50, or, 200, km))}}}
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