Đáp án đúng: D
Giải chi tiết:\(\begin{array}{l}\,x - \frac{3}{7} = \frac{{ - 13}}{{14}}\\\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\, = \frac{{ - 13}}{{14}} + \frac{3}{7}\\\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\, = \frac{{ - 1}}{2}\end{array}\)
Vậy \(x = \frac{{ - 1}}{2}\)
Chọn D