1、( 1)4,3

(2) parallelogram

(3)6,3

2,4 * 4 * 3.14 divided by 2=25. 12 cm2.

10* 10= 100 cm2

3.( 12+8)* 2 = 40m 20 * 3. 14 = 62.8m。

4、 1+3+5+7+9

=5*5

=25

Page 47:

1. The number of girls is 4/5 of that of boys, 5/9 of that of boys and 4/9 of that of girls.

Xiaoming's weight is 9/8 of Xiaoxing's, Xiaoxing's weight is 8/9, Xiaoxing's weight is lighter than Xiaoming's 1/9.

2, column equation:

Solution: Suppose there are X black rabbits.

7/5x=35

x=35*5/7

x=25

There are 25 black rabbits.

Find out "how many parts of a black rabbit are white rabbits" before solving.

7/5 divided by 1=5/7.

35*5/7=25

There are 25 black rabbits.

3800 divided by (9+ 1)=80 grams.

A: It contains 80 grams of salt.

Page 48:

1、 1/2,3/8,25/49

2. The yellow ribbon is 5/9 shorter than the red ribbon, and the length of the red ribbon is 5/4 longer than the yellow ribbon. The remaining four-thirds are used, and the remaining three-quarters are used.

3、 1/2+ 1/6+ 1/ 12+ 1/20+ 1/30

= 1- 1/2+ 1/2- 1/3+ 1/3- 1/4+ 1/4- 1/5+ 1/5- 1/6

= 1- 1/6

=5/6

4、 1/2+ 1/4+ 1/8+ 1/ 16+ 1/32

= 1- 1/32

=3 1/32

This is what the teacher said. It must be right.