Let's formalize the idea of variables. Variable A variable is a letter of symbol (like x , y , or ) that represents the varying value of a quantity. When defining a variable to represent the value of a quantity, it is important to: be descriptive about what quantity you are measuring, which often includes indicating where the quantity is being measured from; state the unit of measure. Let's return to the candle burning situation and think about appropriate ways to define variables in the situation. Untried Recall that a 14-inch candle is lit and steadily burns until it is burned out. Which of the following are appropriate variable definitions in this situation? Select all that apply. Let b represent the burned length of the candle. Let b represent the burned length of the candle (in inches). Let r represent the length (in inches). Let r represent the remaining length of the candle (in inches). Let t represent the number of hours since the candle was lit. Let t represent time