There are 4 classes in Grade Five. It was planned to plant X trees in each class, but in fact, five more trees were planted in each class, and 1 * * * trees were planted.
3. The average of A, B and C is 2.2, the number of A is 1.6, and the average of B and C is (? )。
4. During the summer vacation, Xiaoming went to the garden to meet four students, A, B, C and D. Xiaoming shook hands with all four students, A shook hands with three people, B shook hands with two people, and C shook hands with 1 person, so Ding and (? ) People shook hands.
5. Weight of a barrel of oil 12kg. Half of the oil is sold, and the barrel weighs 6.75kg. If the price per kilogram of oil is 4.2 yuan, can you get () yuan by selling all the oil?