Phương pháp giải:

Áp dụng quy tắc chuyển vế đổi dấu để làm tìm x.

Lời giải chi tiết:

\(\eqalign{ & {\rm{ }}\,(4x + 5):3 - 121:11 = 4  \cr & \,\,\,\,\,\,\,\,(4x + 5):3 - 11\,\,\,\,\,\,\,\,\,\,\,\,\, = 4  \cr  & \,\,\,\,\,\,\,\,(4x + 5):3\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 4 + 11  \cr & \,\,\,\,\,\,\,\,(4x + 5):3\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 15  \cr  & \,\,\,\,\,\,\,\,\,4x + 5\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 15.3  \cr & \,\,\,\,\,\,\,\,\,4x + 5\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 45  \cr & \,\,\,\,\,\,\,\,\,4x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 45 - 5  \cr & \,\,\,\,\,\,\,\,\,4x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 40  \cr & \,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 40:4  \cr & \,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 10 \cr} \)

vậy x =10