Giúp mình làm bài 11 với.

Đáp án:

`(1/4+3/4+2/8)+(-5/13+(-8)/13)`

`=1+2/8-1`

`=2/8`

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`(-7)/31+24/19+1/15+7/31+(-5)/19`

`=((-7)/31+7/31)+(24/19+(-5)/19)+1/15`

`=0+1+1/15`

`=15/15+1/15`

`=16/15`

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`(-46)/43+5/17+11/17+3/43+1/17`

`=((-46)/43+3/43)+(5/17+11/17+1/17)`

`=-1+1`

`=0`

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`(21/31+(-16)/7)+(44/53+10/31)+9/53`

`=21/31+(-16)/7+44/53+10/31+9/53`

`=(21/31+10/31)+(44/53+9/53)+(-16)/7`

`=1+1-16/7`

`=2-16/7`

`=14/7-16/7`

`=-2/7`

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`(15/16+13/33+1/11)+(7/33+(-15)/16+20/66)`

`=15/16+13/33+3/33+7/33+(-15)/16+10/33`

`=(15/16+(-15)/16)+(13/33+3/33+7/33+10/33)`

`=-1+1`

`=0`