Question 858933
This question seems to expect ignoring whether the percents are as volume per volume, weight per volume, or weight per weight.  Continuing anyway, the question IN GENERAL is discussed and answered in this lesson:


<a href="http://www.algebra.com/tutors/Mixtures%3A-All-in-Symbols.lesson?content_action=show_dev">.  Click and follow this link.  Mixing two concentrations for known amount of mixture</a>.  

Learn that, and you can then answer ALL two part mixture questions which fit this form.