math
posted by adrian .
ratios in systems of equations

Since this is not my area of expertise, I searched Google under the key words "ratios 'systems of equations'" to get these possible sources:
http://en.wikipedia.org/wiki/Simultaneous_equation
http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/SolvingSystemsofEquationsSimultaneousEquations.topicArticleId9046,articleId9042.html
http://www.explorelearning.com/View/correlations/Textbooks/Books/BCElemandInterAlg2002.html
http://canmin.geoscienceworld.org/cgi/content/abstract/32/4/969
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.