SOLUTION: To produce 20 liters of a 45% alcohol solution by mixing together a 60% solution and a 35% solution, how many liters of a 60% solution should be used?

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Question 358567: To produce 20 liters of a 45% alcohol solution by mixing together a 60% solution and a 35% solution, how many liters of a 60% solution should be used?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!

Let A be the amount of 60% solution, B the amount of 35% solution.
1.A%2BB=20
.
.
.
60A%2B35B=45%2820%29
2.12A%2B7B=180
Multiply eq. 1 by (-7) and add to eq. 2 to eliminate B and solve for A.
-7A-7B%2B12A%2B7B=-140%2B180
5A=40
highlight%28A=8%29liters.