\[\boxed{\text{1272.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[x + x - 1 + y + 2 + z - 4 = 5\]
\[2x + y + z = 8\]
\[2x + x - 1 + y + 2 = 8\]
\[3x + y = 7\]
\[3x + x - 1 = 7\]
\[4x = 8,\ \ x = 2\]
\[y = - 1 + x,\ \ y = 1\]
\[z = 2 + y,\ \ z = 3\]
\[u = - 4 + z,\ \ u = - 1\]
\[v = - 1 + u,\ \ v = - 2\]
\[Ответ:x = 2,\ y = 1,\ z = 3,\]
\[\ u = - 1,\ v = - 2.\]