\[\boxed{\text{6.243.}}\]
\[\textbf{а)}\ 27,2 - (y - 2,8) = 22,4\]
\[y - 2,8 = 27,2 - 22,4\]
\[y - 2,8 = 4,8\]
\[y = 4,8 + 2,8\]
\[y = 7,6.\ \]
\[Ответ:7,6.\ \]
\[\textbf{б)}\ 46,48 - (5,6 + z) = 36,48\]
\[5,6 + z = 46,48 - 36,48\]
\[5,6 + z = 10\]
\[z = 10 - 5,6\]
\[z = 4,4.\ \]
\[Ответ:4,4.\]