Question 506102
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The amount of pure acid in the 35% solution is 0.35 times *[tex \Large x], the amount of pure acid in the 60% solution is 0.60 times *[tex \Large y], and the amount of pure acid in the final 45% solution is 0.45 times 70 since the total amount at the end is 70 liters.  And *[tex \Large 0.45\ \times\ 70\ =\ 31.5].


By the way, I wouldn't introduce the second variable at all.  You can save yourself a step by saying that *[tex \Large x] represents the amount of 35% solution and then, since the total amount of solution is 70 liters, the amount of 60% solution has to be *[tex \Large 70\ -\ x].  That way my single equation for this problem comes out to:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 0.35x\ +\ 0.60\left(70\ -\ x\right)\ =\ 31.5]


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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