Question 181588
<font face="Times New Roman" size="+2">

The total amount of solution has to be 12 ounces, so let the amount of 4% solution be <i>x</i> ounces and the amount of 12% solution be 12 - <i>x</i> ounces.


4% of the <i>x</i> ounces of 4% solution is pure acid.  12% of the 12 - <i>x</i> ounces of 12% solution is pure acid.  When you add these two together, you get something that is 9% times 12 ounces pure acid.  Symbolically,


*[tex \Large \text {          }\math 0.04x + 0.12(12 - x) = 0.09*12]


Solve for <i>x</i> to get the amount of 4% solution.  Subtract this result from 12 to get the amount of 12% solution.  Hint:  This will be much easier to avoid errors if you first multiply both sides of the equation by 100 to get rid of the decimal fractions.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
</font>