\[Страница\ 77\]
\[\boxed{\mathbf{145.}}\]
\[9 + 10 - 7 = 19 - 7 = 12\]
\[18 + 10 - 7 = 28 - 7 = 21\]
\[20 + 10 - 7 = 30 - 7 = 23\]
\[42 + 10 - 7 = 52 - 7 = 45\]
\[63 + 10 - 7 = 63 + 3 = 66\]
\[\boxed{\mathbf{146.}}\]
\[1)\ 3 - 1 - 1 = 1\ м.\]
\[2)\ 3 - 2 + 1 = 2\ м.\]
\[3)\ 3 + 1 + 1 = 5\ м.\]