Đáp án đúng: C
Giải chi tiết:\(\begin{array}{l}\,\,\,\,\,450:15 = 450:\left( {5 \times 3} \right)\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 450:5:3\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,\,\,\,\,90\,\,\,\,\,\,\,\,\,:3\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \,\,\,30\end{array}\)
Chọn C