5. 28 ◯ 7 = 21

28 - 7 = 21

(13 - 9) ◯ 5 = 20 => 4 * 5 = 20

8 ◯ 4 = 32 => 8 * 4 = 32

8 ◯ 4 = 2 => 8 - 4 = 4, 8 / 4 = 2. Верный ответ: 8 / 4 = 2.

28 ◯ 7 = 35 => 28 + 7 = 35

(30 - 27) ◯ 4 = 12 => 3 * 4 = 12