SOLUTION: how many gallons of a 50% antifreeze soltuion must be mixed with 70 gallons of 15% antifreeze to get a mixture that is 40% antifreeze

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Question 274705: how many gallons of a 50% antifreeze soltuion must be mixed with 70 gallons of 15% antifreeze to get a mixture that is 40% antifreeze
Found 2 solutions by scott8148, checkley77:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
(50%)(x) + (15%)(70) = (40%)(70 + x)

Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
.50x+.15*70=.40(70+x)
.50x+10.5=28+.40x
.50x-.40x=28-10.5
.10x=17.5
x=17.5/.10
x=175 gal of 50% antifreeze is used.
Proof:
.50*175+.15*70=.40(70+175)
87.5+10.5=.40*245
98=98