Okay. So,to solve this, we should set up a proportion. 20/9 = 30/x. Do some cross multiplication to get 20x = 270. Now, divide each side by 20 to isolate the x. 270/20 is 13.5. A 30 lb dog weighs about 13.5 kilograms. The unit rate is about 2.22 pounds per 1 kilogram. Ratio is something about comparison, while unit rate is more precise and to the point.