The number of milligrams of a certain medicine a veterinarian gives to a dog varies directly with the weight of the dog. If the veterinarian gives a 30-pound dog Three-fifths milligram of the medicine, which equation relates the weight, w, and the dosage, d?

d = StartFraction 1 Over 50 EndFraction w
d = three-fifths w
d = 18 w
d = 50 w

The correct equation is:

d = three-fifths w

The correct equation that relates the weight, w, and the dosage, d, is:

d = three-fifths w