\[Страница\ 78.\]
\[\boxed{\mathbf{1.}}\]
\[7 + 6 = 13\]
\[18 - 9 = 9\]
\[14 - 5 = 9\]
\[11 - 8 = 3\]
\[4 + 8 = 12\]
\[5 + 6 = 11\]
\[13 - 4 = 9\]
\[15 - 7 = 8\]
\[6 + 8 = 14\]
\[3 + 9 = 12\]
\[8 + 8 = 16\]
\[16 - 9 = 7\]
\[Мне\ понадобилось\ 2\ минуты.\]
\[\boxed{\mathbf{2.}}\]
\[24 + 5 = 29\]
\[49 - 7 = 42\]
\[78 - 70 = 8\]
\[37 + 9 = 46\]
\[63 - 8 = 55\]
\[58 + 3 = 61\]
\[54 + 6 = 60\]
\[70 - 4 = 66\]
\[86 - 60 = 26\]
\[\boxed{\mathbf{3.}}\]
\[\boxed{\mathbf{4.}}\]
\[Длина\ ломаной:\]
\[2 + 3 = 5\ см.\]
\[Периметр\ треугольника:\]
\[2 + 3 + 4 = 9\ см.\]