\[Страница\ 22.\]
\[\boxed{\mathbf{3}.}\]
\[\textbf{а)}\ 7 - 5\]
\[\textbf{б)}\ 6 - 6\]
\[\textbf{в)}\ 4 - 0\]
\[\boxed{\mathbf{4}.}\]
\[\textbf{а)}\ 23 - 8 = 15\]
\[15 + 8 = 23 \rightarrow верно;\]
\[23 - 15 = 8 \rightarrow верно.\]
\[\textbf{б)}\ 61 - 29 = 42\]
\[42 + 29 = 71 \rightarrow неверно;\]
\[61 - 42 = 19 \rightarrow неверно.\]
\[\textbf{в)}\ 84 - 47 = 37\]
\[47 + 37 = 84 \rightarrow верно;\]
\[84 - 37 = 47 \rightarrow верно.\]
\[\boxed{\mathbf{5}.}\]
\[\textbf{а)}\ 98 - 59 = 39\ км.\]
\[\textbf{б)}\ 63 - 25 = 38\ см.\]
\[\textbf{в)}\ 102 - (26 + 57) =\]
\[= 102 - 83 = 19\ м.\]
\[\textbf{г)}\ 150 - (48 + 55) =\]
\[= 150 - 103 = 47\ м.\]