SOLUTION: I have one solution of 70% acid 30% water and another that is 20% acid 80% water. How much of each would I need to attain 5 ounces of 65% acid 35% water.

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Question 370043: I have one solution of 70% acid 30% water and another that is 20% acid 80% water. How much of each would I need to attain 5 ounces of 65% acid 35% water.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the amount of 70% solution, B the amount of 20% solution.
Volume:
1.A%2BB=5
.
.
Concentration:
70A%2B20B=65%285%29
2.14A%2B4B=65
Multiply eq. 1 by (-4) and add to eq. 2,
-4A-4B%2B14A%2B4B=20%2B65
10A=85
A=85%2F10
highlight%28A=17%2F5%29 ounces
.
.
Then from eq. 1,
17%2F5%2BB=5
highlight%28B=8%2F5%29 ounces