Final answer:
The correct equation to calculate the total cost of an order of n shirts, taking into account Ms. Carter's pricing strategy, is 12n + 70, which includes both a variable cost for each shirt and a fixed cost per order.
Step-by-step explanation:
The problem given pertains to a situation where Ms. Carter makes shirts and has a particular pricing strategy. She charges a fixed cost of $70 per order, plus an additional $12 for every shirt ordered. When faced with the question "Which equation could be used to calculate the cost (in dollars) of an order of n shirts?", you need to consider both the variable cost per shirt and the fixed cost per order. The cost of n shirts would be the number of shirts, n, multiplied by the price per shirt, which is $12. Then you add the fixed cost of $70, which is not dependent on the number of shirts ordered.
The correct equation from the provided options that represents this situation is the first one:
This equation is used to calculate the total cost of an order of n shirts, combining both the variable and fixed costs.