SOLUTION: How many liters of 20% alcohol solution should be added to 40 liters of a 50% alcohol solution to make a 30% solution?

Question 550577: How many liters of 20% alcohol solution should be added to 40 liters of a 50% alcohol solution to make a 30% solution?
Found 2 solutions by josmiceli, mathstutor494:
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = liters of 20% solution needed
given:
liters of alcohol in 50% solution
liters of alcohol in 20% solution
-------------

80 liters of 20% solution are needed
check:

OK

Answer by mathstutor494(120) (Show Source): You can put this solution on YOUR website!
Let quantity of 20% alcohol solution be added : x liters
Eqn for altered solution ....
> x*20% + 40 * 50% = (x+40) * 30%
> x*0.2 + 40*0.5 = (x+40)*0.3 ..(converting percentages into decimal)

> 0.2x + 20 = 0.3x + 12
> 20-12 = 0.3x - 0.2x (Rearranging similar terms)
> 8 = 0.1 x
Hence x = 8/0.1
Ans 80 Litres

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