1.① Prime numbers are rational numbers. So the data is physical and chemical, and 23 1 has three factors: 3,7, 1 1, which are consistent. So it's 3,7, 1 1.

② Let the denominator be X and the numerator be X-9. Equation (X-9)/ X =7/ 10 X=30, so the molecule is 2 1 and the fraction is 2 1/30.

2. Saw for 4 times and get 5 segments, each segment is10/1*1/5 = 2/11.

3. When 0.75A = 0.6B = C, that is, 3/4 A=3/5 B=3/3C molecules are the same, the larger the denominator, the smaller the score. So c is the smallest, from small to large cab.

4. If bag B has x kilograms, then bag A is 0.8X. Get the equation from the problem

0.8X+6=X X=30, so A is 24 and B is 30.

5.2.5 Divided by five sevenths =3.5

6. The minimum prime number of the last sentence is 2. Then the age of the son may be 10, 1 1 20. Suppose the father's age is X.

Then the mother is1112x and the son is112x *1/3 =1/.

Because the age is an integer, only 1 1 meets the above three data. So father 36, mother 33, son 1 1.

7. let the total distance be x.

Car 0.5X X-0.5X=0.5X left. Bicycle 0.5X*0.25=0. 125X.

So what's left to go is x-0.5x-0.125x = 0.375x.

0.375X/X=0.375 or 3/8.