Question 275795
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Tutor @josgarithmetic provides a response showing her favorite multiple-variable formula for solving 2-part mixture problems like this.  Use that method if you love using formulas without having any understanding of how you are solving the problem.<br>
Tutor @ikleyn provides a response showing a typical formal algebraic method for solving such problems.  That is perfect if what you want is a formal algebraic solution method.<br>
An informal (and usually faster) method for solving this kind of problem uses the logical fact that the ratio in which the two ingredients need to be mixed is exactly determined by where the target percentage lies between the two given percentages.<br>
For this particular problem....
(1) Using a number line if it helps, observe/calculate that 45 is 23/58 of the distance from 22 to 80 (22 to 45 is a difference of 23; 22 to 80 is a difference of 58)
(2) That means that 23/58 of the mixture must be the higher percentage ingredient<br>
{{{(23/58)*11.6=23(11.6/58)=23(.2)=4.6}}}<br>
ANSWER: The mixture should be made using 4.6 fl. oz. of the 80% acid solution and (11.6-4.6) = 7.0 fl. oz. of the 22% acid solution<br>