1. There are 98 story books in the library. Today, 46 books were lent out and 25 books were returned. How many story books are there in the library now?

Answer: 98-(46-25)=77 copies.

2. A children's coat is 48.5 yuan, a pair of trousers is cheaper than a coat in 9.8 yuan, and a skirt is more expensive than trousers in 2.5 yuan. How much is this skirt?

Answer: 48.5-9.8+2.5=4 1.2 yuan.

Dad took Xiaoming skiing. It took him four minutes to climb the mountain by cable car, which travels 200 meters per minute. It took 20 minutes to ski downhill, walking 70 meters per minute. How many meters is skiing more than taking a cable car?

Answer: 20×70-4×200=600 km.

4. The length of the highway from a county to the provincial capital is160km. The speed of the car is 80 km/h on the expressway and 40 km/h on the ordinary highway. How much time does it save to take the expressway from the county seat to the provincial capital than the ordinary highway?

Answer: 160 40-80 40 = 2 hours.

5. Datong Township Central Primary School planted trees on barren hills. In 2002, it planted 356 trees. In 2003, trees were planted three times, each time 140 plants. In what year were many trees planted? How much more?

Answer:140× 3 = 420,420-356 = 64, more than in 2003.

Thoughts on solving application problems;

(1) There are some application problems of method of substitution. Give the relationship between two or more unknowns and ask for these unknowns. When thinking, we can replace another unknown with one unknown according to the conditions given in the question, thus simplifying the relationship between data volumes. So as to find a solution to the problem.

(2) Hypothetical method Some application problems need two or more unknowns. When thinking, you need to put forward some assumptions first, and then calculate according to the known quantity in the stem. According to the contradiction of data volume, make appropriate adjustments and finally find the correct answer.