What is a good strategy for finding the distance between two numbers on a number line?

You can find the constant of proportionality by finding the ratio of

Find the values of y: 3y^3(y^2+ 2/3y)=0

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?