Câu 2 (1.5 điểm): Tìm x biết: a) $\frac{2}{3}x$ + $\frac{1}{3}$ = $\frac{-5}{7}$  b) $2,2 + 2,5x = -0,3$ c) $x: \frac{3}{2}$- $\frac{1}{2}$= $\frac{1}{3}$ 

`a) 2/3x + 1/3 = -5/7`

`<=> 2/3x = -5/7 - 1/3`

`<=> 2/3x = -22/21`

`<=> x = -11/7`

Vậy `x = -11/7`

`b) 2,2 + 2,5x = -0,3`

`<=> 2,5x = -0,3 - 2,2`

`<=> 2,5x = -2,5`

`<=> x = -1`

Vậy `x = -1`

`c) x : 3/2 - 1/2 = 1/3`

`<=> x . 2/3 = 1/3 + 1/2`

`<=> 2/3x = 5/6`

`<=> x = 5/4`

Vậy `x = 5/4`