Question 852915
If the concentrations are as volume per volume or as mass/volume then this system works:


u = amount of 18% acid
v = amount of 45% acid


{{{(18u+45v)/12=36}}} and {{{u+v=12}}}
<a href="http://www.algebra.com/algebra/homework/word/mixtures/Mixtures%3A-All-in-Symbols.lesson">See this linked lesson for more about this type.</a>