Đáp án đúng: B
Giải chi tiết:\(\begin{align} & a)\,\,23\times 75+25\times 23+180~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~b)\,\,20+\text{ }\!\![\!\!\text{ 60 }-\text{ (10}-\text{5}{{\text{)}}^{2}}\text{ }\!\!]\!\!\text{ } \\ & \,\,\,\,\,\text{=}\,23\times (75+25)+180~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\,\,\,\,\,\,\,\,\,\,\,\,=20+\text{ }\!\![\!\!\text{ 60 }-\text{ }{{\text{5}}^{2}}\text{ }\!\!]\!\!\text{ } \\ & \,\,\,\,\,\text{=}\,23\times 100+180~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=20+\text{ }\!\![\!\!\text{ 60 }-\text{ 25 }\!\!]\!\!\text{ } \\ & \,\,\,\,\,\text{=}\,2300+180~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=20+\,35 \\ & \,\,\,\,\,\text{=}\,2480~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,=55 \\\end{align}\)
Chọn B