SOLUTION: how much salt should be added to a 20L of 20% salt solution to increase it to a 25% salt solution

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Question 941402: how much salt should be added to a 20L of 20% salt solution to increase it to a 25% salt solution
Answer by srinivas.g(540) About Me  (Show Source):
You can put this solution on YOUR website!
Let us assume x liters of salt is added to 20 % of 20 L solution
salt already present in the solution = 20 % of 20 L
=+%2820%2F100%29%2A20
= 4 L
after adding x liters of salt , total quantity of solution becomes x+20 liters
after adding salt , total quantity of slat = 25 % of (20+x)
= %2825%2F100%29%2A%2820%2Bx%29
it should be equal to the sum of salt already present + salt added
+%2825%2F100%29%2A%2820%2Bx%29=4%2Bx
%2820%2Bx%29%2F4=4%2Bx
multiply with 4 on both sides
%28%2820%2Bx%29%2F4%29%2A4=%284%2Bx%29%2A4
20+x= 4*4+4*x
20+x= 16+4x
20=16+4x-x
20=16+3x
20-16 = 3x
4=3x
x=4/3
x=1.33 L
Result : amount of salt to be added =1.33 Liters