\[\boxed{\text{253.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[x = 760 - 290\]
\[x = 470.\]
\[x = 540 - 260\]
\[x = 280.\]
\[x = 600 - 370\]
\[x = 230.\]
\[x = 900 - 850\]
\[x = 50.\ \]