\[Страница\ 80.\ Верно?Неверно?\]
\[\boxed{\mathbf{1}\mathbf{.}\mathbf{\ }}\]
\[340 + 20 = 360 \neq 520\]
\[неверно.\]
\[\boxed{\mathbf{2}\mathbf{.}\mathbf{\ }}\]
\[860 - 400 = 460\]
\[верно.\]
\[\boxed{\mathbf{3}\mathbf{.}\mathbf{\ }}\]
\[700 - 600 = 100\]
\[верно.\]
\[\boxed{\mathbf{4}\mathbf{.}\mathbf{\ }}\]
\[980 - 30 = 950 \neq 650\]
\[неверно.\]
\[\boxed{\mathbf{5}\mathbf{.}\mathbf{\ }}\]
\[170 + 300 = 470\]
\[верно.\]
\[\boxed{\mathbf{6}\mathbf{.}\mathbf{\ }}\]
\[400 - 300 = 100 = 1\ сот.\]
\[верно.\]
\[\boxed{\mathbf{7}\mathbf{.}\mathbf{\ }}\]
\[9\ сот - 3\ сот = 6\ сот = 600\]
\[верно.\]
\[\boxed{\mathbf{8}\mathbf{.}\mathbf{\ }}\]
\[340 + 60 = 400 \neq 240 + 60\]
\[неверно.\]
\[\boxed{\mathbf{9}\mathbf{.}\mathbf{\ }}\]
\[8\ сот - 3\ дес = 800 - 30 = 770\]
\[верно.\]
\[\boxed{\mathbf{10}\mathbf{.}\mathbf{\ }}\]
\[970 - 500 = 470 > 370\]
\[верно.\]
\[\boxed{\mathbf{11}\mathbf{.}\mathbf{\ }}\]
\[840 - 700 = 140 < 150\]
\[270 + 700 = 970 > 960\]
\[700 + 300 = 1000\]
\[700 - 50 = 650\]
\[верно.\]