If a portion of a half water/half alcohol mix is replaced with 25% alcohol solution, resulting in a 30% alcohol solution, what percentage of the original alcohol was replaced?	Pick one:
A) 3%
B) 20%
C) 66%
D) 75%
E) 80%
let x be water, y - alcohol. so we have -   0.5x+0.5y -0.25y=0.3x+0.3y   x=1/4y   x/y=1/4   so in a new solution y 's portion is 4/5 or 80%   ANSW80%R:80%
<result>E</result>
If a portion of a half water/half alcohol mix is replaced with 25% alcohol solution, resulting in a 30% alcohol solution, what percentage of the original alcohol was replaced?