Tìm x

​​​​​​$$\begin{gathered} Tìm x, biết: \\ \frac{7}{(x+3)\times (x+10)}+\frac{11}{(x+10)\times (x+21)}+\frac{13}{(x+21)\times (x+34)}=\frac{x}{(x+3)\times (x+34)} \end{gathered}$$