\[Стр.\ 41.\]
\[\boxed{\mathbf{10.}}\]
\[при\ y > - 1.\]
\[\boxed{\mathbf{11.}}\]
\[\textbf{а)} - 1 + ( - 7);\ \ \]
\[\textbf{б)}\ ( - 2,5) + ( - 5,5);\ \ \ \]
\[\textbf{в)}\ \left( - \frac{1}{3}\ \right) + \left( - 7\frac{2}{3} \right).\]
\[\boxed{\mathbf{12.}}\]
\[\textbf{а)}\ ( - 8) + ( - 10);\ \ \]
\[\textbf{б)}\ 3 + ( - 21);\ \ \ \]
\[\textbf{в)} - 21 + 3.\]
\[\boxed{\mathbf{13.}}\]
\[\textbf{а)}\ x - 10 = - 2\]
\[x = - 2 + 10\]
\[x = 8\]
\[Ответ:8.\]
\[\textbf{б)}\ y - 13 = - 37\ \]
\[y = - 37 + 13\]
\[y = - 24\ \]
\[Ответ:\ - 24.\]
\[\textbf{в)}\ y - 46,79 = - 10,5\]
\[y = - 10,5 + 46,79\]
\[y = 36,29\]
\[Ответ:36,29.\]
\[\textbf{г)}\ a - 5\frac{3}{8} = - 10\frac{5}{8}\ \]
\[a = - 10\frac{5}{8} + 5\frac{3}{8}\]
\[a = - 5\frac{1}{4}\]
\[Ответ:\ - 5\frac{1}{4}.\]