Question 842959
The assumption used will be that the percents given are as weight per volume for the saline solutions.


{{{(12u+20v)/16=15}}} and {{{u+v=16}}}


More thorough instruction is :
"Mixing two concentrations for known amount of mixture",
http://www.algebra.com/tutors/Mixtures%3A-All-in-Symbols.lesson?content_action=show_dev