Question 942679
Check this lesson carefully because it deals more generally with the type of question you want the help for:


<a href="http://www.algebra.com/my/mixture-price-two-part-both-parts-unknown.lesson?content_action=show_dev">Two-Part Mixture Problem, how much of each</a>
http://www.algebra.com/my/mixture-price-two-part-both-parts-unknown.lesson?content_action=show_dev