Đề bài: tìm x bt sos với!!! :(( làm đến câu 17thui cx đc

`11) 1/3 + 1/2 : x = -4`

`1/2 :x = -4 - 1/3`

`x = 1/2 : (-13/3)`

`x = -3/26`

`12) 3/4 +1/4 : x = 2/5`

`1/4 : x = 2/5 - 3/4`

`x = 1/4 : (-7/20)`

`x = -5/7`

`13) x : (-9)/2 = -4/25`

`x = -4/25 xx (-9)/2`

`x = 18/25`

`14) 5/7 + 2/7 : x = 1`

`2/7 : x = 1 - 5/7`

`x = 2/7 : 2/7`

`x = 1`

`15) 2/5 x - 1/3 = -2`

`2/5 x = -2 + 1/3`

`x = -5/3 : 2/5`

`x = -75/77`

`16) 5/7 : x - 2/5 = 1/3`

`5/7 : x = 1/3 + 2/5`

`x = 5/7 : 11/15`

`x = 25/77`

`17) |-5/14| - x : 6/11 = -3/7`

`5/14  - x : 6/11 = -3/7`

`x : 6/11 = 5/14 + 3/7`

`x = 11/14 . 6/11`

`x = 3/7`

`18) x - 1/2 = 3 1/2 : 2/7`

`x - 1/2 = 7/2 : 2/7`

`x - 1/2 = 49/4`

`x = 49/4 + 1/2`

`x = 51/4`

`19) 1/3 x + 2/5 (x - 1) = 0`

`1/3 x + 2/5 x - 2/5 = 0`

`(1/3 + 2/5) x - 2/5 = 0`

`11/15 x - 2/5 = 0`

`11/15 x = 0 + 2/5`

`x = 2/5 : 11/15`

`x = 6/11`

`20) (1/4 x  -1) - (5/6 x + 2) - (1-5/8 x) = 3`

`1/4 x - 1 - 5/6 x - 2 - 1 + 5/8 x = 3`

`(1/4 - 5/6 + 5/8)x - 1 - 2 -1 = 3`

`1/24 x - 1 - 2-1 = 3`

`1/24 x - 4 = 3`

`1/24 x = 3+4`

`x = 7 : 1/24`

`x = 168`

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