SOLUTION: How many gallons of a 90% antifreeze solution must be mixed with 90 gallons of 30% antifreeze to get a mixture that is 80% antifreeze? The word problem on this site that is exac

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Question 843242: How many gallons of a 90% antifreeze solution must be mixed with 90 gallons of 30% antifreeze to get a mixture that is 80% antifreeze?
The word problem on this site that is exactly the same, gives a wrong answer of 480 gallons????
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

How many gallons highlight_green%28x%29 of a 90% antifreeze solution must be mixed 

with 90 gallons of 30% antifreeze to get a mixture that is 80% antifreeze?

   .90x + .30(90gal) = .80(90gal + x)

          x =  .50(90gal)/.10 = 450gal