SOLUTION: please help me solve this mixture problem. Thanks! Maricar has a solution that is 60% alcohol and another solution that is 60% alcohol. If maricar wants 12 gallons of a solutio

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Question 631713: please help me solve this mixture problem. Thanks!
Maricar has a solution that is 60% alcohol and another solution that is 60% alcohol. If maricar wants 12 gallons of a solution that is 45% alcohol, how many gallons of the 40% solution and of the 60% solution should be mix together to obtain her 45% solution?
Answer by Maths68(1474) About Me  (Show Source):
You can put this solution on YOUR website!
Solution A
=========
Amount = x
Concentration =40% =0.4

Solution B
=========
Amount = 12-x
Concentration =60% = 0.6
Mixture
========
Amount =12
Concentration =45%=0.45
[Amount Solution A * Concentration A] + [Amount Solution B * Concentration of B] = [Amount of Mixture *Concentration of Mixture]
(x)(0.4)+(12-x)(0.6)=(12)(0.45)
0.4x+7.2-0.6x=5.4
-0.2x+7.2=5.4
-0.2x=-1.8
-0.2x/-0.2=-1.8/-0.2
x=9


Solution A
=========
Amount = x = 9 gallons
Concentration =40% =0.4
Solution B
=========
Amount = 12-x = 12-9 = 3 gallons
Concentration =60% = 0.6


9 gallons of the 40% solution and 3 gallons of the 60% solution should be mix together to obtain 12 gallons of 45% solution?