<PRE><B>Question 969630</B>
x=amount of water in kg.  (0 salt)

start with 20 kg at .03 (3%) (salt)=.60 

add x kg of water with 0 salt.

will have (20 + x) kg of water with 2 % salt.  
Distribute.  02* (20+x)=0.4 +0.02x 

This will equal .60,  the desired concentration.

So, 0.4 +0.02x=.60   

Multiply the whole equation by 100.  Not necessary, but will be easier to work with

40 + 2 x=60
Subtract 40 from both sides

2x=20
Divide by 2 on both sides.

x=10 liters.

Check.  We are decreasing the concentration 1/3.

We add 10 liters of water to 20, and the final amount, 30, has 1/3 less salt, and 1/3 of it was without salt.  


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