Question 570766
Solution A 
Amount = x grams
Concentration =100% =1 (It is pure salt)

Solution B
Amount = 60 grams 
Concentration =20% = 0.2

Resultant Solution
Amount = (60+x) grams 
Concentration =25%=0.25

[Amount Solution A * Concentration A] + [Amount Solution B * Concentration of B] = Amount of Resultant * Concentration of resultant
(x)(1)+(60)(0.2)=(60+x)(0.25)
x+12=15+0.25x
x-0.25x=15-12
0.75x/0.75=3/0.75
x=4



We need to add 4 grams of salt to increase the salt content to 25%