A. Equation 3a-6=3b+5 Divide two sides by 3 to get equation a-2=b+5.

B Subtract x-3 from both sides of equation 7x=5x+3 to get equation 6x-3=4x+6.

C. divide both sides of equation -5=0. 1x by 0. 1 to get equation x=0.5.

D. if -2=x, then x=-2.

(2) Solve equation 20-3x=5, and the correct one after shifting the term is ().

A.-3x = 5+20 b . 20-5 = 3x c . 3x = 5-20d .-3x =-5-20

(3) It is correct to solve the equation -x=-30 and convert the coefficient into 1 ()

A.-x=30 B.x=-30 C.x=30 D

(4) When solving the equation, the following deformation is relatively simple ()

A. Multiply both sides of the equation by 20 to get 4(5x- 120)= 140.

B, separating the two sides of the equation to obtain

C. remove the brackets and get x-24=7.

D, sorting equations, and obtaining

Example 2.

(1) If the formulas 3nxm+2y4 and -mx5yn- 1 can be combined into one term, try to find the value of m+n. ..

(2) The number of the following merge errors is ()

①5x 6+8x 6 = 13x 12②3a+2b = 5ab③8 y2-3 y2 = 5④6 anb 2n-6 a2 nbn = 0

1 (B)2 (C)3 (D)4。

Example 3. Solve the following equation

( 1)8-9x=9-8x (2)

(3) (4)

1. When pouring cement column, the construction personnel should bend the steel bar into a square. If the area of each square is 400 square centimeters, which steel bar should be selected in the table below?

Model A B C D

Length (cm) 90 70 82 95

Both Party A and Party B are running at a constant speed on the 400-meter circular track, starting from the same place and heading in the same direction at the same time. The speed of Party A is 100 m/min, which is 3/2 times that of Party A. How long did it take them to meet for the first time (2)?

3. In order to encourage water conservation in a certain place, the monthly water fee is charged according to the following provisions: if the monthly water consumption of each household does not exceed 20 tons, each ton of water will be charged at 1.2 yuan; If the monthly water consumption of each household exceeds 20 tons, the excess will be charged at 2 yuan per ton. If a user's water fee in May averages per ton 1.5 yuan, how much should the user pay in May?

4. For a project, it takes 10 days for Party A to do it alone, 15 days for Party B to do it alone, and 5 days for Party A to do it alone, and then Party A and Party B cooperate to complete it, and * * * gets 1 0,000 yuan. If the remuneration is calculated according to the workload completed by each person, how should Party A and Party B distribute it?

5. When Xiaohua Hua 10 painted the bedroom, the percentage of completed workload was recorded as follows:

Time (hours) 1 2 3 4 5 6 7 8 9 10

Percentage of completion 5 25 35 50 50 65 70 80 95 100

(1) For the fifth time, he completed% of the workload;

(2) Xiaohua completed the maximum workload in time;

(3) If Xiaohua starts working at 8: 00 a.m., then he has no work at that time.

1. Let a, b and c be real numbers, and | A |+A = 0, | AB | = AB, | C |-C = 0, and find the value of the algebraic formula | B |-| A+B |-C-B |+| A-C |.

2. Add "+,-,"and brackets to "5, 5, 1" to make the calculation result 24. This formula is in favor of 62| Comment (8).