Giải thích các bước giải:

`a) 4/3 + 2/3 : x = (-2)/5`

`2/3 : x = (-2)/5 - 4/3`

`2/3 : x = -6/15 - 20/15`

`2/3 : x = -26/15`

`x = 2/3 : (-26)/15`

`x = 2/3 . (-15)/26`

`x = -5/13`

Vậy, `x = -5/13`

`-----`

`b) 7/3 - 1 3/5x = -1 2/3`

`7/3 - 8/5x = -5/3`

`8/5x = 7/3 - (-5)/3`

`8/5x = 12/3`

`x = 12/3 : 8/5`

`x = 12/3 . 5/8`

`x = 5/2`

Vậy, `x = 5/2`

`-----`

`( -2 1/4 : x + 1,5 )( -5/3x - 5/12 ) = 0`

`( -9/4 : x + 1,5 ) ( -5/3x - 5/12 ) = 0`

`Th_1: -9/4 : x + 1,5 = 0`

`-9/4 : x = -1,5`

`-9/4 : x = -3/2`

`x = -9/4 : (-3)/2`

`x = -9/4 . (-2)/3`

`x = 3/2`

`-----`

`Th_2: -5/3x - 5/12 = 0`

`-5/3x = 5/12`

`x = 5/12 : (-5)/3`

`x = 5/12 . (-3)/5`

`x = -1/4`

Vậy, `x ∈ { 3/2; -1/4 }`

`-----`

`-3/5x - ( x + 2,5 ) = -13/15`

`-3/5x - x - 5/2 = -13/15`

`-3/5x - 5/5x = -13/15 + 5/2`

`-8/5x = -26/30 + 75/30`

`-8/5x = 49/30`

`x = 49/30 : (-8)/5`

`x = 49/30 . (-5)/8`

`x = -49/48`

Vậy, `x = -49/48`

`#tm.`