Question

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Answer 1

d,

$\frac{- 5}{7} . \frac{2}{11} + \frac{5}{7} . \frac{9}{11} = \frac{5}{7} . (\frac{9}{11} - \frac{2}{11}) = \frac{5}{7} . \frac{7}{11} = \frac{5}{11} e, \frac{5}{9} . \frac{7}{13} + \frac{5}{9} . \frac{9}{13} - \frac{5}{9} . \frac{3}{13} = \frac{5}{9} . (\frac{7}{13} + \frac{9}{13} - \frac{3}{13}) = \frac{5}{9} . \frac{13}{13} = \frac{5}{9} f, \frac{- 5}{9} + \frac{8}{15} + \frac{- 2}{11} + \frac{4}{- 9} + \frac{7}{15} = \frac{- 5}{9} + \frac{- 4}{9} + (\frac{8}{15} + \frac{7}{15}) + \frac{- 2}{11} = \frac{- 9}{9} + \frac{15}{15} + \frac{- 2}{11} = - 1 + 1 + \frac{- 2}{11} = 0 + \frac{- 2}{11} = \frac{- 2}{11} g, \frac{7}{19} \times \frac{8}{11} + \frac{3}{11} \times \frac{7}{19} + \frac{- 12}{19} = \frac{7}{19} \times (\frac{8}{11} + \frac{3}{11}) + \frac{- 12}{19} = \frac{7}{19} \times \frac{11}{11} + \frac{- 12}{19} = \frac{7}{19} + \frac{- 12}{19} = \frac{- 5}{19} h, \frac{- 7}{25} \times \frac{39}{- 14} \times \frac{50}{78} = \frac{- 7 \times 39 \times 2 \times 25}{25 \times 2 \times (- 7) \times 2 \times 39} = \frac{1}{2} j, \frac{- 3}{4} + \frac{2}{7} + \frac{- 1}{4} + \frac{3}{5} + \frac{5}{7} = (\frac{- 3}{4} + \frac{- 1}{4}) + (\frac{2}{7} + \frac{5}{7}) + \frac{3}{5} = \frac{- 4}{4} + \frac{7}{7} + \frac{3}{5} = - 1 + 1 + \frac{3}{5} = 0 + \frac{3}{5} = \frac{3}{5}$

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Answer 2

d,

$\frac{- 5}{7} . \frac{2}{11} + \frac{5}{7} . \frac{9}{11} = \frac{5}{7} . (\frac{9}{11} - \frac{2}{11}) = \frac{5}{7} . \frac{7}{11} = \frac{5}{11} e, \frac{5}{9} . \frac{7}{13} + \frac{5}{9} . \frac{9}{13} - \frac{5}{9} . \frac{3}{13} = \frac{5}{9} . (\frac{7}{13} + \frac{9}{13} - \frac{3}{13}) = \frac{5}{9} . \frac{13}{13} = \frac{5}{9} f, \frac{- 5}{9} + \frac{8}{15} + \frac{- 2}{11} + \frac{4}{- 9} + \frac{7}{15} = \frac{- 5}{9} + \frac{- 4}{9} + (\frac{8}{15} + \frac{7}{15}) + \frac{- 2}{11} = \frac{- 9}{9} + \frac{15}{15} + \frac{- 2}{11} = - 1 + 1 + \frac{- 2}{11} = 0 + \frac{- 2}{11} = \frac{- 2}{11} g, \frac{7}{19} \times \frac{8}{11} + \frac{3}{11} \times \frac{7}{19} + \frac{- 12}{19} = \frac{7}{19} \times (\frac{8}{11} + \frac{3}{11}) + \frac{- 12}{19} = \frac{7}{19} \times \frac{11}{11} + \frac{- 12}{19} = \frac{7}{19} + \frac{- 12}{19} = \frac{- 5}{19} h, \frac{- 7}{25} \times \frac{39}{- 14} \times \frac{50}{78} = \frac{- 7 \times 39 \times 2 \times 25}{25 \times 2 \times (- 7) \times 2 \times 39} = \frac{1}{2} j, \frac{- 3}{4} + \frac{2}{7} + \frac{- 1}{4} + \frac{3}{5} + \frac{5}{7} = (\frac{- 3}{4} + \frac{- 1}{4}) + (\frac{2}{7} + \frac{5}{7}) + \frac{3}{5} = \frac{- 4}{4} + \frac{7}{7} + \frac{3}{5} = - 1 + 1 + \frac{3}{5} = 0 + \frac{3}{5} = \frac{3}{5}$

Answer 3

`-2/17 + 15/23 + (-15/17) + 4/9 + 8/23`

`= (-2/17 - 15/17) + (15/23 + 8/23) + 4/9`

`= -1 + 1 + 4/9`

`= 0 + 4/9`

`= 4/9`

`__________`

`5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 4/11`

`= 5/7 . (5/11 + 2/11 - 4/11)`

`= 5/7 . 3/11`

`= 15/77`

`___________`

`-5/9 + 8/15 + (-2/11) + 4/(-9) + 7/15`

`= (-5/9 + 4/(-9)) + (8/15 + 7/15) - 2/11`

`= -1 + 1 - 2/11`

`= 0 - 2/11`

`= -2/11`

`___________`

`s)` `\frac{5}{13}` `+` `\frac{-5}{17}` `+` `\frac{-20}{41}` `+` `\frac{8}{13}` `+` `\frac{-21}{41}`

`=` `( \frac{5}{13} + \frac{8}{13} )` `+` `(\frac{-20}{41} + \frac{-21}{41})` `+` `\frac{-5}{17}`

`=` `1` +`( - 1 )` `+` `\frac{-5}{17}`

`=` `\frac{-5}{17}`

`___________`

`t)` `\frac{1}{5}` `+` `\frac{-2}{9}` `+` `\frac{-7}{9}` `+` `\frac{4}{5}` `+` `\frac{16}{17}`

`=` `(\frac{1}{5} + \frac{4}{5})` `+` `(\frac{-2}{9} + \frac{-7}{9})` `+` `\frac{16}{17}`

`=` `1` `+` `( -1 )` `+` `\frac{16}{17}`

`=` `\frac{16}{17}`

Số thứ tự	Loại hàng	Số lượng (quyển)	Giá đơn vị (đồng)	Tổng số tiền (đồng)
1	Vở loại 1	35	2000	...
2	Vở loại 2	42	1500	...
3	Vở loại 3	38	1200	...
Cộng:				...

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