\[\boxed{\text{251.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[540\ :x = 20\]
\[x = 540\ :20\]
\[x = 54\ :2\]
\[x = 27.\]
\[x \cdot 6 = 18\ 024\]
\[x = 18\ 024\ :6\]
\[x = 3\ 004.\]
\[3\ 480 - x = 730\]
\[x = 3\ 480 - 730\]
\[x = 2\ 750.\]
\[x + 2\ 010 = 12\ 004\]
\[x = 12\ 004 - 2\ 010\]
\[x = 9\ 994.\]