1.2

2.M=5，X = 1； M=3，X = 2； M=2，X = 4；

M=-3，X =- 1； M=- 1，X =-2； M=0，X=-4

3.6

4.40

5.3

6. Two methods

1. Backward deduction: According to the meaning of the question, the eldest daughter is divided into 1, the second son into 2, the eldest son into 4, and the mother into 8, * * * with 15.

Second, the column equation: let * * have x cows.

Judging from the meaning of the question:

1/2{ 1/2[ 1/2( 1/2-0.5)-0.5]-0.5}-0.5=0

1/ 16X = 15/ 16

X= 15

A: * * * There are 15 cows.

7. Let four numbers be x, X+7, X+ 14 and X+2 1 respectively.

X+X+7+X+ 14+X+2 1=46

X= 1

A: The four days are 1, 8, 15, 22 respectively.

8. Let these nine numbers be x, x+ 1, x+2, x+7, x+8, x+9, x+ 14, x+ 15 and x+ 16 respectively.

Then x+x+1+x+2+x+7+x+8+x+9+x+14+x+15+x+16 =17/.

X= 1 1

A: These nine days are 1 1, 12, 13, 18, 19, 20, 25, 26 and 27 respectively.

9. Let the purchase price be a, which means: (1+x%) a = (1+x%+10%) (1-8%) a.

After simplification: (1+x%) a = (0.92 x%+101.2%) a.

0.08X= 1.2

X= 1500

A: X= 1500.

10. If the original price is X yuan, then 0.9X-0.8X=2.

X=20

Answer: The original price of this 10 kg egg is 20 yuan.

Fill in the blank reference method:

1. From the meaning of the question, X+ 1=2X- 1, so X=2.

2. solution: X(M- 1)=4, and x is an integer.

So there are six possibilities.

m- 1 = 4； m- 1 = 2； m- 1 = 1； m- 1 =-4；

m- 1 =-2； M- 1=- 1

So; M=5，X = 1； M=3，X = 2； M=2，X = 4；

M=-3，X =- 1； M=- 1，X =-2； M=0，X=-4

3. from the meaning of the question: k = X.

So 2K+ 1=3.

4K+2=6 (each side multiplied by 2)

4. set a price of x yuan,

The equation is 0.9X= 1.2*30.

X=40

5. From the meaning of the question: 2N-2=N+ 1.

N=3