The answer is 10 milligrams of Medication A. When you divide 18 by 3 for Medication B, you get 6. Then you have to divide 60 by 6 and you get 10 milligrams.
60/18 = A/3....60 in A to 18 in B = x in A to 3 in B cross multiply because this is a proportion (18)(A) = (60)(3) 18A = 180 A = 180/18 A = 10 milligrams <===