SOLUTION: Theresa Morgan, a chemist, has a 20% hydrochloric acid solution and a 50% hydrochloric acid solution. How many liters of each should she mix to get 431.25 liters of a hydrochloric

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Question 1114809: Theresa Morgan, a chemist, has a 20% hydrochloric acid solution and a 50% hydrochloric acid solution. How many liters of each should she mix to get 431.25 liters of a hydrochloric acid solution with a 42% acid concentration?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
system%2820x%2B50y=42%2A431.25%2Cx%2By=431.25%29

system%282x%2B5y=1811.25%2Cx%2By=431.25%29
You might want to use Elimination Method at least for either variable.

system%282x%2B5y=1811.25%2C2x%2B2y=862.5%29

3y=1811.25-862.5
3y=948.75
highlight%28y=316.25%29------------of the 50% HCl
.
highlight%28x=115%29--------------of 20% HCl