#7. a. Discuss the usefulness of a variable (symbol) for representing all the values that a quantity can assume. b. It is important when defining variables that we are specific in describing the varying quantity whose values are being represented by the variable (designated symbol). Is the statement, "d=Erin's distance (in miles)" an adequate definition of a variable? If not, what is missing and how might you modify this statement so that it defines a variable? c. When defining a variable, why is it important to describe where the quantity is being measured from and the measurement unit