SOLUTION: How many gallons of 90% antifreeze would i add to 70 gallons of 20% antifreeze to get a 80% mixture

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Question 475280: How many gallons of 90% antifreeze would i add to 70 gallons of 20% antifreeze to get a 80% mixture
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
0.20*70 + 0.90*x = 0.80*(70 + x)
==> 14 + 0.90x = 56 + 0.80x
==> 0.10x = 42
==> x = 420 gallons of 90% antifreeze must be added.