Answer: Option B
The average value of each article can be calculated as follows:
Total cost of all articles = (number of shirts * cost per shirt) + (number of pairs of shoes * cost per pair of shoes) + (number of pants * cost per pant)= (13 * 50) + (15 * 60) + (12 * 65)= 650 + 900 + 780= 2330
Total number of articles = number of shirts + number of pairs of shoes + number of pants= 13 + 15 + 12= 40
Average value of each article = Total cost of all articles / Total number of articles= 2330 / 40= 58.25
Therefore, the correct option is B, i.e., 58.25.
Some relevant definitions and formulas used in the solution are:

• Average or mean: It is the sum of a set of numbers divided by the total number of numbers in the set.
• Total cost: It is the sum of the individual costs of all items.
• Total number: It is the sum of the individual numbers of all items.

Mathematically, the formulas used in the solution are:

• Total cost = (number of items * cost per item)
• Average value = Total cost / Total number