Second, CAC. 3， 1.x=- 12，2.x= 4/5，

Solution: If there are X cities with severe water shortage, there are 2x cities with general water shortage. Cities that are not short of water for the time being 40x-50. According to the meaning of the question, we can get x+(40x-50)+2x=664 and the solution is x= 102.

Try it: Scheme: Suppose that when the car travels x kilometers every month, the two car rental schemes cost the same. According to the meaning of the question, we can get the following:1210+10x/100 =120x/100.

Solution: x =11.11×100 =100.

Page 3, 1, 1, omitted, 2, 6, 3, 120, 4, 9, 5, 40; 30。 Second, bcc. Third, the solution: let the area of the big rectangle be X and the area of the small rectangle be Y. According to the meaning of the question, we can get the equations: (y-1/5y)+(x-1/7x) = 200, 1/5Y = 1/7x. X= 140，y= 100， 100x 1/5=20。 4. solution: let the cost of each piece of this dress be x, and according to the meaning of the question, it can be obtained: X (1+40%) 80.

Solution: x= 125. Try it: ellipsis.

Solution: x= 125. Try it: ellipsis.

Page 5, 1: 1,-4; 2, 1; 3,24; 4. Omit. Two. Omit. III. X =1; x =- 1/2； x =- 10/7； X=2 1/ 17。 Four. Omit. Try 1. Omit, 2. Omit, 3. Solution: we walk for x hours and drive y cars. According to the meaning of the question, we can get: equations; 4x+36y = 56； X+y=2。 The solution is x= 1/2.y=3/2. Page 7, I: 1. x = 3； y=- 1，2.x-2y= 1 1，3.3； 2, 4. Equation: 3x+5y =14; 2x+4y =10.2: Ba. Three: 1.x= 15, y= 17. 2.x= 10/3, y=8, 3.x=29/20, y=7/40, 4.x = 1 3, y=5. Try it:1. Solution: Suppose that X people passed and Y people failed in this competition. According to the meaning of the question, we can get the equations, x+y= 120, 76x+52y= 120×66. Solution: x=70, y=50. 2. Solution: Let 2 yuan have Y and 5 yuan have X. According to the meaning of the question, we can get the equations, y+x+20+7=58, (1x20)+(7x10)+2y+5x = 200. Solution: x = 65438.

Page 9: 1, 1. Equation, 3x+4y=84, 2x+3y = 48；; 2.5,3; 3. 13,8; 4. Equation, 7x+4y=500, 9x+6y = 680；; Second, ellipsis. Third: the solution; Let the original price of the first book be X and the original price of the second book be Y yuan. According to the meaning of the question, we can get: equations, x+y=880, 0.8x+0.75y=880-200. Solution: x=400, y=480. Give it a try: 1 Solution: let it be cut into adult X.2. Judging from the question 1, the first type: 24x 10+ 12=252 (yuan) and the second type: 5x24+ 12x 13=276 (yuan). Page 1 1:1.5a ≤10,2. 1,4; -4.-3.-2.- 1。 Second: CDDD. 4. 1.x≥3，2。 X≥3 for solution 1 and x > 1/2 for solution 2.

Try it: ellipsis.

Page 13:1:1.8; 2.8; 3.35 ,35 ; 4.30 < x < 170； Two: CA3. Ellipsis; Third: the solution; At △FBD, ∵DF⊥AB, ∴1= 90 and ∠ D = 43, and ∠d+∠ 1+∞.

∴∠ B = 180-∠ 1-∠ D = 47, ∠2 is the external angle of △ABC ∴∠ 2 =∠a+∞. ∫∠3 is the outer corner of △DCL, ∴∠3=∠d+∠c∫∠∠ 1+∠2+∠3 = 360. 2. Omit.

F = 3602. Omit.

Page 15: 1,1.120; 2.60 ; 3.34 。 Two: BDDCC. Three: (in the figure, 14△BFC, bottom angle left ∠3, right ∠4) Solution: ∠A+∠ 1+∠2+∠3+∞ in △ABC. V: 147. 6. Solution: Let a small rectangle be x in length and y in width. According to the meaning of the question, we can get the equation: 5y = 2x7y+4x = 68: x =10; Y=4, ∴ small rectangle S:10× 4 = 40; Give it a try:1.c; ; 2. Omit.

Page 18:1; 1.8; 2. 1 1; 3. Triangle, hexagon and octagon; 4.6; 5.45 。 Two: BC. Third: the solution; The degree of this external angle is 180- 144 = 36. So: 360 ÷ 36 = 10, 10+2= 12.

Four: 360× 5 = 1800, (1800 ÷180)+2 =12.

Try it: ellipsis. Page 20:1:1:1.2.3.5.6; 2: Garden. Two: BD. Third, ellipsis. Four: ellipsis. Five: ellipsis. Try it: ellipsis.

Page 22:1:1.120; 2.30 。 Two: CA. Write it yourself at the back. It's simple. Mostly cartography and probability problems.