2.5 and 16

3. Chicken: 16 Rabbit: 14

4.5 cents: 24 yuan coins: 26.

5.300

6.{2y=x

{(x+y) 15=3*2*π

7.A

8.C

9.B

10. Suppose A has X books and B has Y books.

{4(y-5)+y-5=x+5

{x-5=3(y+5)

x=95

y=25

1 1. Let the original price of commodity A be X yuan and that of commodity B be Y yuan.

{( 1- 10%)x+( 1+40%)

{x+y= 100

x= 16

y=84

12. Set X people to process the frames and Y people to process the lenses.

{x+y=28

{68x: 102y= 1:2

x= 12

y= 16

13. the mountain road is x kilometers, and the flat road is y kilometers.

{x/ 12+y/9= 1

{x/8+y/9= 1.25

x=6

y=9/2