SOLUTION: Ben recently moved from southern California to northern Alaska. After consulting with a local mechanic, Ben realized that his car radiator fluid should consist of 70% antifreeze. C

Question 343459: Ben recently moved from southern California to northern Alaska. After consulting with a local mechanic, Ben realized that his car radiator fluid should consist of 70% antifreeze. Currently, his 4.5-L radiator is full, with a concentration of 40% antifreeze. How much coolant should be drained and filled with pure antifreeze to reach the desired concentration?

My answer:
I know that I need to find out how much coolant to drain and how much antifreeze to add.
let x= liters needed to drain
let 4.5-x=how much to add
(4.5-x)(.70)=(4.5-x)(.40)
315-70x=180-40x
135=30x
x=4.5
take 4.5 and divide by 2= 2.25Liters to drain and 2.25 Liters to fill
is this answer correct in how i solved it?
Answer by scott8148(6628) (Show Source): You can put this solution on YOUR website!
the amount drained and filled is the same
___ x liters of coolant is drained , leaving 4.5-x liters of 40%
___ x liters of pure antifreeze (100%) is then added , making 4.5 liters of 70%

(40%)(4.5 - x) + (100%)(x) = (70%)(4.5)
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