Question 906017
How many gallons of 80% antifreeze solution must be mixed with 90 gallons of 15% antifreeze solution to get a mixture that is 70%?
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let x=amt of 80% solution to mix

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80%x+15%*90=70%(90+x)
.80x+13.5=63+.70x
.10x=49.5
x=495          
amt of 80% solution to mix with 90% solution=495 gallons