Question 985941
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300 ounces at 12% contains:
0.12(300oz)=36 ounces of acid
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300oz-100oz=200 ounces
After 100 ounces of water evaporates, the 36 ounces of acid is in 200 ounces of solution. 
(36 ounces/200 ounces)(100%)=18% 
The solution after 100 ounces of water evaporates is 18% acid.