We are given that some water is added to a gallon of 10% saline to create 2% solution.
Let us assume x gallons of water is added in 10% of a gallon of saline.
Therefore,
10% of 1 gallon = 2 % of (solutions of x gallons of water + saline).
0.1 = 0.02 (x+1)
0.1 = 0.02x +0.02
Subtracting 0.02 from both sides, we get
0.1 -0.02= 0.02x +0.02 -0.02
0.08 = 0.02x
Dividing both sides by 0.02, we get
0.08/0.02 = 0.02x/0.02
