\[\boxed{\mathbf{712\ (712)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ 210\ :7 \cdot 3 = 30 \cdot 3 =\]
\[= 90 - это\ \frac{3}{7}\ числа\ 90.\]
\[2)\ 90\ :2 \cdot 3 = 45 \cdot 3 =\]
\[= 135 - искомое\ число.\]
\[Ответ:135.\]
\[\boxed{\mathbf{712}.}\]
\[1)\ 6 = 2 \cdot 3;\ \ \ 10 = 2 \cdot 5\]
\[НОК(6;10) = 2 \cdot 3 \cdot 5 = 30.\]
\[2)\ 9 = 3²;\ \ 12 = 2² \cdot 3\]
\[НОК(9;12) = 3^{2} \cdot 2^{2} = 36.\]
\[3)\ 14 = 2 \cdot 7;\ \ \ 28 = 2^{2} \cdot 7\]
\[НОК(14;28) = 2^{2} \cdot 7 = 28.\]
\[4)\ 8 = 2^{3};\ \ 9 = 3^{2}\]
\[НОК(8;9) = 2^{3} \cdot 3^{2} = 72.\]
\[5)\ 32 = 2^{5};\ \ \ 48 = 2^{4} \cdot 3\]
\[НОК(32;48) = 2^{5} \cdot 3 = 32 \cdot 3 =\]
\[= 96.\]
\[6)\ 8 = 2^{3};\ \ 9 = 3^{2};\ \ \ 15 = 3 \cdot 5\ \]
\[НОК(8;9;15) = 2^{3} \cdot 3^{2} \cdot 5 =\]
\[= 8 \cdot 9 \cdot 5 = 40 \cdot 9 = 360.\]