Bài 194:

`a. 17/6 - ( 3/7 + 5/6 )`

`= 17/6 - ( 18/42 + 35/42 )`

`= 17/6 - 53/42`

`= 119/42 - 53/42`

`= 66/42`

`b. 17/6 - 3/7 - 5/6`

`= 119/42 - 18/42 + 35/42`

`= 136/42`

So sánh:

Vì `66/42 < 136/42`

nên `17/6 - ( 3/7 + 5/6 ) < 17/6 - 3/7 - 5/6`

hay `a < b`

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Bài 195:

`a) x + 2/5 = 3/2`

`x = 3/2 - 2/5`

`x = 15/10 - 4/10`

`x = 11/10`

`b) 4/7 + x = 2/3`

`x = 2/3 - 4/7`

`x = 14/21 - 12/21`

`x = 2/21`

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Bài 196:

`a) y - 4/5 = 3/4`

`y = 3/4 + 4/5`

`y = 15/20 + 16/20`

`y = 31/20`

`b) 27/16 - y = 5/4`

`y = 27/16 - 5/4`

`y = 27/16 - 20/16`

`y = 7/16`

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Bài 197:

`x/13 + 15/26 = 46/52`

`x/13 = 46/52 - 15/26`

`x/13 = 46/52 - 30/52`

`x/13 = 4/13`

`x = 4`

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Bài 198:

`y/27 - 2/9 = 6/18`

`y/27 = 2/9 + 6/18`

`y/27 = 4/18 + 6/18`

`y/27 = 5/9`

`y/27 = 15/27`

`y = 15`