SOLUTION: how many liters of 40% and 80% acids must be mixed in order to make 20 liters of a 55% acid solution?

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Question 234919: how many liters of 40% and 80% acids must be mixed in order to make 20 liters of a 55% acid solution?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = the number of liters of 40% acid solution, then (20-x) = the number of liters of 80% acid solution. The sum of these is = 20 liters of 55% acid solution.
This can be expressed algebraically, after converting the percentages to their decimal equivalents, as:
0.4x+0.8(20-x) = 0.55(20) Simplify the left side.
0.4x+16-0.8x = 11 Combine like-terms.
-0.4x+16 = 11 Subtract 16 from both sides.
-0.4x = -5 Divide both sides by -0.4
highlight%28x+=+12.5%29 and...
highlight%28%2820-x%29+=+7.5%29
You would need to mix 12.5 liters of 40% acid solution with 7.5 liters of 80% acid solution to obtain 20 liters of 55% acid soltion.