Cho x, y, z khác 0 thỏa mãn

$$\begin{gathered} \mathrm{Cho} \mathrm{x},\mathrm{y},\mathrm{z} \mathrm{khác} 0 \mathrm{thỏa} \mathrm{mãn}: \frac{\mathrm{y}+\mathrm{z}-\mathrm{x}}{\mathrm{x}}=\frac{\mathrm{x}+\mathrm{x}-\mathrm{y}}{\mathrm{y}}=\frac{\mathrm{x}+\mathrm{y}-\mathrm{x}}{\mathrm{z}}. \\ \mathrm{Tính} \mathrm{B}=(1+\frac{\mathrm{x}}{\mathrm{y}})(1+\frac{\mathrm{y}}{\mathrm{z}})(1+\frac{\mathrm{z}}{\mathrm{x}}) \end{gathered}$$