The answer is A, developed nations make up about 20 percent of population yet consume 75 percent of sources.
So you already have the formula for calculating the dosage for child with: C = a/(a+12)x 180 ml Not sure why you have double brackets
variables are: a = child's age, so everywhere you have an "a" replace it with the age of child.
Example: 5 year old child
C = 5/(5+12)*180= 5/(17)*180 = 5/3060 = .0016 ml or milligrams