



 
Hi Carol, The technique here is to first decide which of the unknown quantities you and to designate by a letter. Here the important unknown quantities are the number of women and women who where on the train in Erie. Thus I would let $W$ be the number of women on the train in Erie and $M$ be the number of men on the train in Erie.
Said in terms of $W$ and $M$ that is \[W = 2 \times M.\]
In terms of $W$ how many women are on the train now? In terms of $M$ how many men are in the train now? There are the same number so know you have a second equation in $W$ and $M.$ Solve for $W$ and $M.$ Make sure you verify your answer.
 


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