2. На двух полках стояли 13 книг. На первой полке — 4 книги. Сколько книг было на второй полке? Подбери к задаче подходящий чертёж. Отметь его.

The problem describes a situation where the total number of books (13) is known, and the number of books on one shelf (4) is known. The task is to find the number of books on the other shelf. This is a subtraction problem: Total books - Books on first shelf = Books on second shelf. Therefore, 13 - 4 = 9. The diagram that represents this is the one showing a total of 13, with a part of 4, and the remaining part as '?'. The second diagram shows a total of 13, with a part of 4, and the remaining part as '?'. The first diagram shows 12 as a known part, which is incorrect. The second diagram shows 4 as a known part and 13 as the total, with '?' as the unknown part. This matches the problem.

13 - 4 = 9

The second diagram is the correct one.