$19 is only added once because there is only one DVD purchased. $14 is added an unknown number of times, thus the variable X is included. We know that that the total number of dollars spent for both items is either less than or equal to 65. (Depending on your teacher, they may want you to write "19 + 14x < 65" if they want you to write the answer only for discrete numbers).
Since the "leading" runner in a race would be found in the first position, because he or she is in the lead, it means they are first, then I suppose I would find the "leading coefficient" in the first place in a polynomial as well.
