SOLUTION: How many gallons of an 80% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 70% antifreeze?

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Question 620192: How many gallons of an 80% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 70% antifreeze?
Found 2 solutions by fcabanski, stanbon:
Answer by fcabanski(1391) About Me  (Show Source):
You can put this solution on YOUR website!
The formula for a concentrated mixture is


% times gallons (1) + % times gallons (2) / gallons (1+2) = New mixture %.


%28.8x+%2B+100%2A.3%29%2F%28100+%2B+x%29+=+.7


.8x + 30 = 70 + .7x


.1x = 40


x = 400

Hope the solution helped. Sometimes you need more than a solution. Contact fcabanski@hotmail.com for online, private tutoring, or personalized problem solving (quick for groups of problems.)


Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
How many gallons of an 80% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 70% antifreeze?
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Equation:
anti + anti = anti
0.80x + 0.30*100 = 0.70*(x+100)
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80x + 30*100 = 70x + 70*100
10x = 40*100
x = 400 gallons (amt. of 80% solution to add)
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Cheers,
Stan H.