12×3+20=36+20=56 (page)
A: From day 6, page 57.
2. Four children send each other 1 card. A * * *, how many cards do you want to send? If you shake hands with each other, how many times do you shake hands?
4×3= 12 (Zhang) 3+2+ 1=6 (times)
A: A * * * will issue a 12 card and shake hands with each other six times.
3. Red Star Primary School plans to collect 120kg tree species in 20 days. In fact, 2 kilograms were collected every day than originally planned. How many days did it actually take to collect these trees?
120 ÷ (120 ÷ 20+2) =120 ÷ 8 =15 (days)
A: It actually took 15 days to collect these tree species.
I bought 280 Jin of rice in the canteen and planned to eat it for 7 days. In fact, I eat 5 kilograms less than planned every day. How many days did this batch of rice actually eat?
280 ÷ (280 ÷ 7-5) = 280 ÷ 35 = 8 (days)
A: This batch of rice was actually eaten for 8 days.
Xiaoling read a 290-page novel, and read 20 pages every day for the first 4 days. How many days can you finish reading 30 pages a day?
(290—4×20)÷30=2 10÷30=7 (days)
A: It will be finished in seven days.
6. A binding team binds 2640 books and binds 240 books in 3 hours. According to this calculation, how many hours will the remaining books be bound?
(2640—240)÷(240÷3)
=2400÷80
=30 (hours)
A: It will take another 30 hours for the remaining books to be bound.
7. There are 84 children's palace choirs, with three times as many dance teams as the choirs, 15. How many people are there in the dance team?
84× 3+15 = 252+15 = 267 (person)
A: There are 267 people in the dance team.
8. The number of science and technology books in the school library is twice that of literature and art books, 47 books and 495 books. How many books are there?
(495-47) ÷ 2 = 448 ÷ 2 = 224 (Ben)
A: There are 224 literary books.
9. An express train departs from Tianjin with an average speed of 79 kilometers per hour; At the same time, there is a slow train from Jinan with an average speed of 40 kilometers per hour. How many kilometers is the railway from Tianjin to Jinan three hours after the two cars meet?
(79+40) × 3 =119× 3 = 357 (km)
A: The railway from Tianjin to Jinan is 357 kilometers long.