The amount of salt she needs to add to the original drink is 1 liter
The given parameters;
original volume of the solution, v = 20 liters
original percentage of salt solution, = 20%
final concentration of the salt, = 25%
The actual amount of salt in the original solution
= 20 x 0.2 = 4
Let the new amount of salt to be added in order to increase its concentration to 25% = x
[tex]\frac{x + 4}{4} = 1.25\\\\x+ 4 = 5\\\\x = 5 - 4\\\\x = 1[/tex]
Thus, the amount of salt she needs to add to the original drink is 1 liter
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