Question 1118152
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Distance = rate times time:<br>
{{{12 = (x-5)(2x)}}}<br>
{{{6 = (x-5)(x)}}}  (note this is equivalent to taking the given information, that the train travels 12 km in 2x hours, and by simple logic changing it to having the train travel 6 km in x hours)<br>
{{{6 = x^2-5x}}}
{{{x^2-5x-6 = 0}}}
{{{x-6)(x+1) = 0}}}<br>
The train's speed is either 6 km/hr or -1 km/hr; I think we can rule out the negative speed....