Đáp án đúng: C
Giải chi tiết:\(\eqalign{& \,5x + 73.21 = 73.26 \cr & \,\,\,\,\,\,5x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 73.26 - 73.21 \cr & \,\,\,\,\,\,5x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 73.\left( {26 - 21} \right) \cr & \,\,\,\,\,\,5x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 73.5 \cr & \,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 73.5:5 \cr & \,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 73 \cr} \)
Vậy x = 73