2. Question 1: What is the speed? (Answer: Speed 2 times 80 equals 160 km/h)

Question 2: What is the speed of the express train? Answer: the speed of the express train is equal to 160 times 3 plus 20 equals 500 kilometers per hour.

3. The school can save 435 times 4 a year, which is equal to 1740 tons.

4.25 There are two 10, that is to say, two were given when buying, so the teacher needs to buy 23, so the total * * * needs 23 times 90, which is equal to 1980 yuan.

5.( 1) 108 divided by 18 is equal to 6, that is to say, 6 yuan is per kilogram for Class A fruits, while 84 divided by 12 for Class B fruits is equal to 7 yuan, so Class A fruits are cheap.

(2) At least 36 times 6 equals 2 16 yuan.

6.( 1) The Sweet Family has four adults and one child, so the round-trip fare is (48 times 4 plus 24 yuan, which is equal to 2 16 yuan) times 2, which is equal to 432 yuan.

(2)59 divided by 3 and multiplied by 2 is approximately equal to 40 yuan.