SOLUTION: Hello theres one question on my alegebra that i just cannot figure it's: How many liters of water must be added to 30liters of a 20% alcohol solution to dilute it to a 15% solution

Question 346723: Hello theres one question on my alegebra that i just cannot figure it's: How many liters of water must be added to 30liters of a 20% alcohol solution to dilute it to a 15% solution?
Found 2 solutions by nerdybill, ewatrrr:
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
How many liters of water must be added to 30liters of a 20% alcohol solution to dilute it to a 15% solution?
.
Let x = liters of water to add
then
"amt of alcohol at start" = "amt of alcohol at end"
.20(30) = .15(30+x)
6 = 4.5+.15x
1.5 = .15x
1.5/.15 = x
10 liters = x

Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
Hi,
*Note: the 20% tells us how much of the original 30L TOTAL mixture is alcohol!
That is: .20*30L = 6L
That tells us we have 6L of alcohol to use for the New Mixture.
.
The question states the new mixture is to be a 15% acohol Mixture
Let M be the TOTAL amount Liters in the new mixture.
.
That is: .15*M = 6L
.
Solve for M
M = 40L We had 30L, need to add 10L of water.
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