Question 252173
All mixture problems are just variations of the standard RTD problems. We need 3 columns labeled: % , L, %L. Next we need three rows labeled A, B, and Mix. The A and B stand for the percentages of what you need. We set up the following table based on the information given. The table doesn't show up very well. BIG SPACE means place a big space between the terms. The % numbers should line up under the percentage sign (%). The liter numbers should line up under the liter sign (L). The %L terms should line up under the %L sign.

              % BIG SPACE              L     BIG SPACE               %L
A  BIG SPACE        80     BIG SPACE          X         BIG SPACE          80X

B  BIG SPACE        30      BIG SPACE   9200-X   BIG SPACE         276000 - 30X

Mix BIG SPACE     62      BIG SPACE   9200        BIG SPACE        570400

Where did all of this stuff come from? 80 = % acid in one solution; 30 = % acid in another solution; 9200 the total number of liters in the mixture; 62 = % needed in the mixture.  Now for the variable. We don't know the exact number of liters for A or B, so we call one of them X. The other will always be 
total liters - X. Finally column 3 (%L): I got these number by multiplying each % and L information.

Next step is to add the first 2 terms of the %L column and set equal to the last term. So, we get

80X + 276000 - 30X = 570400

50X = 294400

X = 5888 L. So we need 5,888 L of the 80% solution.

9200-X = 3112L. We need 3,112L of the 30% solution.