SOLUTION: Anas teacher has asked her too add acid to 8 gallons of a 32% acid in water solution to get a solution which is 69 and 7/9 ( sixty nine and seventh ninths percent) acid. How much p

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Question 305287: Anas teacher has asked her too add acid to 8 gallons of a 32% acid in water solution to get a solution which is 69 and 7/9 ( sixty nine and seventh ninths percent) acid. How much pure acid should she add
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Let A be the number of gallons of 100% acid that gets added.
69%2B7%2F9=628%2F9
Write the concentration equation for the mixture,
100%2AA%2B32%2A8=%28628%2F9%29%28A%2B8%29
Multiply both side by 9.
900A%2B2304=628A%2B5024
272A=2720
A=10
Add 10 gallons of 100% acid.