A candle that is 18 inches tall is lit. As the candle burns, its height decreases at a rate of 0.7 inches per hour. Let t represent the varying number of hours that have elapsed since the candle started burning. Write an expression to represent the varying value of the quantity described in each part. Each expression should be written in terms of the appropriate variable.
Write an expression to represent the varying length of candle (in inches) that has burned since the candle started burning.