1.( 1) Length 4 Width 3

(2) parallelogram

(3) Length 6 width 3

2.S=πr？ ÷2=3. 14×4? ÷2=25. 12cm？ s = 10× 10 = 100cm？

3.C =( 12+8)×2 = 40m C =πd = 3. 14×20 = 62.8dm

4. 1+3+5+7+9=5×5=25

Su Jiaoban 47 pages

1.( 1) 4/5 5/9 4/9

(2) 9/8 8/9 1/9

2.( 1) solution: there are x black rabbits.

7/5 x=35, so x=25.

There are 25 black rabbits.

(2) The black rabbit is 5/7 of the white rabbit, 5/7×35=25.

3. 1+9 = 10 800÷ 10 = 80 80× 1 = 80g。

Answer: 80 grams of salt.