Question 1188015
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Here is a quick and easy method for solving any "mixture" problem like this if the numbers are "nice" (and if a formal algebraic solution is not required).<br>
(1) On a number line, the 34% is 3/4 of the way from 7% to 43%.  (7 to 43 is a difference of 36; 7 to 34 is a difference of 27; 27/36 = 3/4.)
(2) That means 3/4 of the mixture needs to be the 43% ingredient.<br>
ANSWER: 3/4 of 120ml, or 90ml, of 43%; the other 30ml of 7%<br>
CHECK:
0.34(120) = 40.8
0.43(90)+0.07(30) = 38.7+2.1 = 40.8<br>