Phương pháp giải:

Thực hiện các phép tính để tìm số chưa biết x.

Lời giải chi tiết:

\(\begin{array}{l}165 - \left( {35:x + 3} \right).19 = 13\\\,\,\,\,\,\,\,\,\,\,\,\,\left( {35:x + 3} \right).19 = 165 - 13\\\,\,\,\,\,\,\,\,\,\,\,\,\,\left( {35:x + 3} \right).19 = 152\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,35:x + 3\,\,\,\,\,\,\,\,\,\,\,\, = 152:19\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,35:x + 3\,\,\,\,\,\,\,\,\,\,\,\, = 8\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,35:x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 8 - 3\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,35:x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 5\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 35:5\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 7\,\,\,\,\,\,\,\,\,\,\end{array}\)

Chọn A.