SOLUTION: How many gallons of a solution that is 75% antifreeze must be mixed with 4 gallons of a 30% solution to obtain a mixture that is 60% antifreeze

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Question 464540: How many gallons of a solution that is 75% antifreeze must be mixed with 4 gallons of a 30% solution to obtain a mixture that is 60% antifreeze
Answer by mpc12381(4) About Me  (Show Source):
You can put this solution on YOUR website!
Let x be the amount of 75% antifreeze
75%(x)+30% (4gallons) = 60%(x+4)
0.75x + 0.3(4) = 0.6(x+4)
0.75x + 1.2 = 0.6x + 2.4
0.75x - 0.6x = 2.4 - 1.2
0.15x = 1.2
x = 1.2 / 0.15
x = 8 gallons of 75% solution