Two formulas that approximate the dosage of a drug prescribed for children are shown below. In the​ formulas, Aequalsthe ​child's age, in​ years, Dequalsan adult​ dosage, and Cequalsthe proper​ child's dosage. The formulas apply for ages 2 through​ 13, inclusive. For a 3​-year-old ​child, what is the difference in the dosage given by​ Cowling's rule and​ Young's rule? Express the answer as a single rational expression in terms of D. Then describe what your answer means in terms of the variables in the models. ​Young's Rule: Upper C equals StartFraction DA Over Upper A plus 12 EndFraction ​Cowling's Rule: Upper C equals StartFraction Upper D left parenthesis Upper A plus 1 right parenthesis Over 24 EndFraction