Fourth, skillfully solve the equation. (4 points for each question, ***20 points)

( 1)2x+0.5x = 20(2)2x-0.5 = 7.5(3)6x+2.3 = 1 1.3

X cm

(4)5×2.4+3x=28.5 (5) The area is 240 square centimeters.

(Equation first, then solution)

48 cm

Fifth, practical operation. (15)

1, and find the surface area and volume of the following graph (8 points)

Eight decimetres and six decimetres.

6 decimeters

5 decimeters 6 decimeters

5 decimeters

2. Stick the following five pieces of glass in an uncovered goldfish bowl. Please calculate how much water this goldfish bowl can hold at most. (4 points)

Three points, three points and seven points.

5 5 5

divide and rule

Mimi Mimi

3 3

divide

Mimi

Seven decimetres. Seven decimetres.

3. There are 1, 2 ..., 9 9 cards. All you have to do is take out three cards and you can form a three-digit number. If you exchange the positions of three cards at will, the three digits can be divisible by three. The three cards you selected are _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. (3 points)

Sixth, solve the problem. (1-4 with 6 points, 5 with 4 points, 6 with 7 with 34 points)

1. No.1 well in Bao Hua Coal Mine mined 35 1 10,000 tons of coal last year, 22,000 tons less than No.2 well. How many tens of thousands of tons of coal were mined in No.2 well last year? (Equation solution)

2. Pingjiang City built 5.6 million square meters of commercial housing this year and last year, and the area of commercial housing built this year is four times that of last year. How many square meters of commercial housing will be built in two years? (Equation solution)

3. Two ships, A and B, are heading towards each other at the same time from two docks which are 384 kilometers apart. The speed of ship A is 2 1 km, and that of ship B is 27km. A few hours later, the two ships met. (Equation solution)

During the "Eleventh" period, the school painted the roof and walls of every classroom. According to the survey, the classroom of Class 6 (2) is 8m long, 6m wide and 3.5m high, with blackboard, doors and windows * * * 14m 2. If 0.8kg of paint is used per square meter, how many kilograms of paint will be used to paint the classroom of Class Six (2)?

3, a section of 5 meters long, 4 meters wide, 3 meters high ventilation pipe, put it on the outside, if every square meter.

Paint 100g. How many kilograms of paint does it take to make this ventilation pipe?

6. After learning the volume, my father tested Xiaoming's study and asked Xiaoming to calculate the volume of a potato at home. After careful consideration, Xiao Ming decided to adopt the following methods to measure (as shown in the picture). Can you calculate the size of potatoes according to the pictures?

2 decimeter

6 cm 8 cm

1 decimeter

7. If the height of a cuboid is cut off by 2cm, the surface area will be reduced by 48cm2, and the rest will become a cube. What is the volume of the original cuboid?