If Nancy wants to be prepared for long term then she will buy the pack of five to save more money. And if she wants to be prepared for a shorter period of time then she will buy the pack of two which may be a little less but will not last as long. But if Nancy is on a budget and can not afford to buy the long term or short term pack then she will buy the single pack. The most cost effective would be the pack of five because the price is reduced, the amount of packaging going to landfills is reduced, it eliminates the need for fancy packaging and single-use plastic. and it allows Nancy to buy the exact amount of what she wants.
C - In any triangle two sides taken together in any manner are greater than the remaining one. So 10+7=17, the greatest length of the 3rd side is 16. 16+17=33