\[\boxed{\mathbf{2.}\mathbf{191}\mathbf{.ОК\ ГДЗ - домашка\ на\ }5}\]
Пояснение.
Решение.
\[\textbf{а)}\ 255 - c + 245 =\]
\[= (255 + 245) - c = 500 - c\]
\[c = 184:\]
\[500 - 184 = 316.\]
\[c = 123:\]
\[500 - 123 = 377.\]
\[\textbf{б)}\ 506 - s - 246 =\]
\[= (506 - 246) - s = 260 - s\]
\[s = 95:\]
\[260 - 95 = 165.\]
\[s = 260:\]
\[260 - 260 = 0.\ \]