Based on the question, here are the information given:
• age of the child (A) = 6 years old
,
• adult dosage (M) = 180 milligrams
To determine the child's dosage in milligrams, a formula is provided. Let's replace "A" and "M" in the formula with the information written above.


Then, solve.
a. First, add 6 and 12 in the denominator.

b. Multiply 6 and 180.

c. Divide 1,080 by 18.

The value of D is 6.
Answer:
Therefore, the prescribed dosage of a certain medicine for a child 6 years old is 6 mg.