Answer:
A. 21d + 48 = 426; 18 days
Step-by-step explanation:
To find the total cost for the month, the number of days (d) must be multiplied by the cost per day (21). That product is added to the admission fee to get the total (426). Only one answer choice has the term 21d. That is the correct answer choice.
21d + 48 = 426; 18 days