Question 433981
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10 gallons of a 15.0% alcohol solution are to be mixed with a 28.0% alcohol solution to make a 20.0% alcohol solution. 
(a) How many gallons of a 28.0% alcohol must be used? 
(b) How many gallons of a 20.0% alcohol solution are made?
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       In the post by @mananth,  his answer to question  (a)  is correct,

       but his answer to question  (b)  is not correct and should be fixed.

       So,  I place below the solution with modified/corrected part for question  (b).



------	Percent	----------------	quantity										
Alcohol	15	----------------10								
Alcohol II	28----------------x								
Total	20	----------------10+x								
													
15*10+28*x=20(10+x)							
150+28x	=200+20	x					
28	x	-	20	x	=	200	-	150	
8x=50										
/8	

								
x=6.25	gallons	28%	Alcohol II must be used. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<<<---=== <U>ANSWER to q.&nbsp;&nbsp;(a)</U>


10+x = 16.25 gallons of the 20% alcohol	are made. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<<<---=== <U>ANSWER to q.&nbsp;&nbsp;(b)</U>