The kind big brother and big sister told me the answers of math 195 to 196.

1 When my son was 9 years old. It can be assumed that the father's age is exactly four times that of his son x years ago, then

4( 13-X)=40-X, X=4, so when my son was 9 years old four years ago, the father's age (36 years old) was exactly four times that of his son.

1. Let the list price of this pair of shoes be X yuan, then 0.8X= 188, and X=235.

3. Let the first number be X, then the second number be X+3+3, that is, X+6, then X+X+6= 100, and the solution is X=47.

So the first number is 47 and the second number is 53.

5. Suppose grandpa wins X sets, then grandson wins (8-X sets). According to the meaning of the question, X=3(8-X) and X=6.

So grandpa won six sets and grandson won two sets.

7. Suppose the area of this wheat field is x hectares. According to the meaning of the question, there is an equation X-25%X-20%( 1-25%)X=6. The solution is X= 10.

9. The original price of one piece is 60/( 1+25%)=48 yuan, and the original price of the other piece is 60/( 1-25%)=80 yuan, 48+80-60X2=8 yuan. So this store went to 8 yuan at a loss.

10. according to the meaning of the question, it is actually the distance traveled by train a. The meeting time is 200/(60+90)=4/3 (hours), so the distance traveled by train A is 60X4/3=80 (kilometers). That is, the place where the two cars meet is 80 kilometers away from one place.

1 1, let the train conductor be l m, the speed be v m/s, 3.6 km/h = 1 m/s. According to the meaning of the question, L= 15(V+ 1), L = 17 (.

12. Let 99 be divided into four numbers: A, B, C and D. According to the meaning of the question, A+2 = B-2 = 2C = D/2 = K...( 1), A+B+C+D = 99...(2)

Substituting (1), A=K-2, B=K+2, C=K/2, D=2K into (2), K-2+K+2+K/2+2K=99, the solution is K=22, so a = 20, b.

1, x=5 is substituted into the equation ax-8=20+a, and 5a-8=20+a is obtained, and a=7 is obtained.

S= 100, SO=25, V= 10 is substituted into the equation S=SO+VT, and 100=25+ 10T is obtained, and T=7.5 is obtained.

2. Suppose he starts to save X yuan, then X (1+2.7%) 3 = 5405, and the solution is X=4990 yuan.

4. If you want to ride X kilometers per hour, then 7.5*( 10-8)=(9-8)X, and the solution is X= 15.

6. Let * * * work together and it takes x hours to complete, then (1/6+1/8) x =1,and the solution is X=24/7.

8. Let Diophantine, a Greek mathematician, be x, then X/6+X/ 12+X/7+5+X/2+4=X and X=84.

Therefore, (1) his age when he got married was 84/6+84/12+84/7 = 33; He died at the age of 84.

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