The problem is about adding water to detergent solution to make a detergent solution.
In the problem g is taken for the number of gallons of water.
So, we can rephrase the given problem in simple words as
g gallons of water is added to 11 gallons of 18% detergent solution to get 12% detergent solution.
Let us write it in form of an equation,
g gallons of water is being added to 11 gallons of solution.
The total amount of solution will be (11 + g) gallons.
11 gallons of 18% detergent solution = 12% detergent solution.
For percent we can write over 100.
Therefore, above equation can be written as
11 × 18/100 = 12/100(g+11)
11 time 18 = 198
Therefore,
198/100 = 12/100(g+11)
Converting 198/100 into decimals, we get 1.98
We can rewrite above eqaution as
1.98 =12/100(g+11)
Dividing both sides by (g+11), we get
Therefore, correct option is D. 1.98/11+g = 12/100.