Đáp án:

 Bài 1 

a ) 6/9 + 24/15 + 12/9 + 6/15

= 34/15 + 12/9+6/15

= 18/5 +6/15

=4

b ) 3 2/9 - ( 1 5/8 + 1 2/9 ) (đổi hết hỗn số sang phân số )

= 29 /9 - ( 13/8 + 11/9)

= 29/9 - 13/8 - 11/9

=155/72 - 11/9

=67/72

Bài 29

a)( 14/5-4/5 ) + ( 7/13+19/13) - (8/9+17/9) 

=10/5 + 2 - 25/9

= 4-25/9

=11/9

b) (164/468 x 432/984) x( 435/164 x 328/435) x 468/432 

= 2/13 x 2 x 13/2 ( rút gọn 468/432)

=4/13 x 13/12

=1/3

Bài 30

a) ( 18 1/2 +5 3/8 -7 5/24) : 16 2/3(đổi hết hỗn số sang phân số )

= ( 37/2 + 43/8 -173/24 ) : 50/3

=50/3 : 50/3

= 1 

b ) 2005x 2007 - 1/ 2004+2005x2006

=4024035 - 1 / 2004 + 4022030

= 4024034/4024034

=1

Bài 28:

`a) 6/9 + 24/15 + 12/9 + 6/15`

`= 34/15 + 12/9+6/15`

`= 18/5 +6/15`

`=4`

`b ) 3 2/9 - ( 1 5/8 + 1 2/9 )`

`= 29 /9 - ( 13/8 + 11/9)`

`= 29/9 - 13/8 - 11/9`

`=155/72 - 11/9`

`=67/72`

Bài 29:

`a)( 14/5-4/5 ) + ( 7/13+19/13) - (8/9+17/9) `

`=10/5 + 2 - 25/9`

`= 4-25/9`

`=11/9`

`b) (164/468 × 432/984) ×( 435/164 × 328/435) × 468/432 `

`= 2/13 × 2 x 13/2 `

`=4/13 × 13/12`

`=1/3`

Bài 30:

`a) ( 18 1/2 +5 3/8 -7 5/24) : 16 2/3`

`= ( 37/2 + 43/8 -173/24 ) : 50/3`

`=50/3 : 50/3`

`= 1`

`b ) 2005× 2007 - 1/ 2004+2005×2006`

`=4024035 - 1 / 2004 + 4022030`

`= 4024034/4024034`

`=1`