Sanya noticed that the temperature was falling at a steady rate of 1.4 degrees every hour after 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? Negative 21 divided by negative 1.4
Negative 1.4 divided by negative 21
Negative 21 divided by 1.4
21 divided by negative 1.4