Hi,         

Let x represent the amount of the 10% Solution, 

then (20L +x) will be the amount of the final solution

Mixing to form the solution***

 .10x + .40*20L = .20(x + 20L)

Solving for x

  .20*20L = .10x

  .20*20L/.10 = x

      40L = x, the amount of the 10% Solution



CHECKING our Answer***

 .10*40 + .40*20 =  4L + 8L = .20*60 = 12 

RELATED QUESTIONS

how many liters of a 10% alcohol solution must be mixed with how many liters of a 50%... (answered by mananth)

how many liters of a 10 alcohol solution must be mixed with 12 liters of a 20% alcohol... (answered by stanbon)

A chemist needs a 20% solution of alcohol.  How many liters of a 10% alcohol solution... (answered by CharlesG2)

how many liters of a 20% alcohol solution must be mixed with 30 liters of a 80% solution... (answered by robertb)

How many liters of a 30% alcohol solution must be mixed with 20 liters of a 70% solution... (answered by Maths68)

how many liters of a 10% alcohol solution must be mixed with 20 L of a 50% solution to... (answered by Alan3354)

how many liters of 40% alcohol solution must be mixed with 20 liters of a 90% solution to  (answered by unlockmath)

How many liters of a 24 percent alcohol solution must be mixed with 20 liters of a 46... (answered by ankor@dixie-net.com)

How many liters of a 14 percent Alcohol Solution must be mixed with 20 liters of a 50... (answered by ewatrrr)