Refer to the answer 1, 1. B 2。 B 3。 C 4 explosive A 5。 D 6。 C 7。 C 8。 14, Chapter 3.4 Level Test B 2, 9.x+7, X+1410.2x; (x+50)； 2x-(x+50) = 7011.5712.15 (x+2) = 33013.120/kloc-. Get 90% ×( 1+20% )x = 270. Get x = 250. So the cost price of this product is 250 yuan. 16. let the average height of students in group a increase by x cm, and that of students in group b increase by (x+2.0 1) cm. According to x =3(x+2.0 1)4- 0.34. Get x = 4.67. Then x+2.0 1 = 6.68. Therefore, the average height growth values of students in group A and group B are 4.67 cm and 6.68 cm respectively. Let's assume the soil and water in the Yangtze River basin. X+(x-29) = 367 ×32.4% is obtained. Get x≈ 74. Therefore, the area of soil erosion in the Yangtze River basin is about 740,000 square kilometers. Fourth, 18. If the price of drugs is reduced by X billion yuan in 2006, it will be reduced by 6 billion yuan in 2009. According to the meaning of the question, we get 54+x+35+40+6x = 269. If x = 20, 6x = 120. Therefore, the amount of drug price reduction in 2006 and 2009 was 2 billion yuan,1200 million yuan and 19 respectively. (65438+. Then wholesale (40-x) kilograms of garlic seedlings. According to the question, it means1.6x+1.8 (40-x) = 70. The solution is x= 10. Then 40-x = 30. As a result, peppers and garlic seedlings were wholesale 10 kg and 30 kg respectively. (2) (2.6-1.6) ×10+(3.3-1.8 )× 30 = 55 yuan. So after selling these peppers and garlic seedlings that day, he can earn 55 yuan. Then sell (50-x) pieces of the second commodity. Get1800x+2 400 (50-x) =108 000. If x = 20, then 50- x = 30. So * * * profit is 200 × 20+300 × 30 = 13 000 (yuan). 2 1. Let Jingjing's mother cut a rectangular piece of cloth for the first time, which is x cm wide. According to the question, it means 35-x = 40-2x. The solution is x = 5. So let's talk about the width of the rectangular cloth cut for the first time. Then sell (50-x) pieces of the second commodity. Get1800x+2 400 (50-x) =108 000. If x = 20, then 50- x = 30. So * * * profit is 200 × 20+300 × 30 = 13 000 (yuan). 2 1. Let Jingjing's mother cut a rectangular piece of cloth for the first time, which is x cm wide. According to the question, it means 35-x = 40-2x. The solution is x = 5. So let's talk about the width of the rectangular cloth cut for the first time.