We can use algebra s=speed and l=length (500+l)/s=20, (1900-l)/s=30 we have that s=48 and l=460 by Adding the equations in order to solve for the first variable. Then we plug this value into the other equations in order to solve for the remaining variables.
so we have the \(\text{speed}=48,\text{ and }\boxed{\text{length of the train}=460m}\)
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