2. The sum of the two bottoms of a trapezoid is 12 cm, the height is 14 cm, and the area is square decimeter?

The base of parallelogram is 24cm and the height is 5cm. The area of a triangle is equal to it and the height is 12 cm. How many centimeters is the base of the triangle?

4. A billboard (with the same contents on both sides), 4m on the top and 6m on the bottom and 2m high. If this advertising company charges 20 yuan per square meter of billboards, how much will it cost?

5. Wang Lin originally had 10 yuan. After giving it to his sister 3.4 yuan, her sister was 0.34 yuan less than him. How much money does her sister have now?

6. A rectangular piece of paper, 25 cm long and 18 cm wide, was cut into two flags of isosceles right triangle with sides of 4 cm. How many sides can I cut at most?

7. A rope is 46 meters long. It needs12.5m for the first time and 223.6m for the second time. How many meters is the rope shorter than the original one?

8. As shown in the figure, the area of triangle ABC is 24 square centimeters, which is twice the area of parallelogram. Find the area of the shadow.

Sixth, comprehensively improve the problem.

1 with 0, 2, 8, 5,? The two decimal places that make up "zero" are not read ().

2, a three-digit decimal, accurate to the percentile is 3.80, the minimum value of this three-digit decimal is (), and the maximum value is ().

3. Carelessly calculate 8.6, add a decimal, and take the plus sign as the minus sign to get 7. 1. The correct result should be ().

Xiao Ming, Gao Xiao and Xiao Liang ran 100 meter. Xiao Ming took 18 seconds, Gao Xiao took 18.2 seconds, Xiao Liang took 17.3 seconds, () first, () third.

5. Press 0.90 on the calculator and press □, □, □, or □ first and then □.

6. Uncle Wang used a wall and a 24-meter rope to enclose a rectangle. What is the largest area of this rectangle () square meters?

7. Li Nainai deposited a sum of money in the bank, which earned 1659.995 yuan, and actually received () yuan.

8. As shown in the figure, the side length of the square ABCD is 40 decimeters, and the ED is 50 decimeters. Find the length of CF ..

9. Uncle Li uses a wall, as shown below, and forms a trapezoid with a 20-meter-long rope. What is the area of this trapezoid?

10, Xiao Wang works in a company. The company stipulates that the annual salary is 23,000 yuan in the first year and will increase by 3,000 yuan every year. What is Xiao Wang's annual salary in the fourth year? How much can he get in four years?