8x+0.2×5=3.4

8x=2.4

x=0.3

A: It burns an average of 0.3 tons per day.

2. In the first question, you said that you used the equation, but you didn't write the second question. I'll just use elementary school arithmetic.

The weight of the four students is 38×4= 152(kg).

After adding Xiaodong, the weight of the five students is * * *

37.6×5= 188 (kg)

Xiaodong's weight is 188- 152=36 (kg).

3. From the meaning of the question, the height ratio of 1 dime to 5/dime is 5: 6, and the height ratio of 1 dime to 1 yuan is 3:4.

The height obtained after equal division is as follows

1 Angle: 5 Angle: 1 Yuan = 15: 18:20.

According to the description of the topic, according to my understanding, the stacked cylinder must be stacked with the same coin, otherwise the side will be uneven, so it is not called a cylinder. So we must first find the least common multiple of 15, 18 and 20, that is, 180.

So the ratio of quantity is 12: 10:9.

The total is 124, so the numbers are 48, 40 and 36 respectively.

48× 0.1+40× 0.5+36×1= 60.8 (yuan)

supplementary question

When 1 and B climb to 4/5, A climbs to the top, and the speed of B is 4/5 of that of A, and 5/4 of B =1.25 times. When B climbs 1.2 meters, A climbs 1.2× 1.25.

2. The first 9 trees are ***24 meters (note that 3×8 should be used instead of 9, because it is the first tree).

Where are the trees?

0、3、6、9、 12、 15、 18、2 1、24

After an interval of 4 meters, where are the trees?

0、4、8、 12、 16、20、24、28……

Therefore, the trees at 0, 12, 24 and 3 need not be pulled up.