Last month kim trained 3 times as many dogs as cats. if the total number of cats and dogs she trained last monthbis 28, how many cats did kim train?

Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour from the time that she first checked her outdoor thermometer. by 6 a.m., the temperature had fallen 21 degrees. which expression can you use to find how many hours earlier she had first checked the thermometer?