Решебник по математике 5 класс Ерина Виленкин рабочая тетрадь Часть 1, 2 Часть 1 | Страница 43

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\[\boxed{\mathbf{18}.}\]

\[a - (b + 3) = a - b - 3 \Longrightarrow\]

\[\Longrightarrow неверно.\]

\[(40 + x) - y = 40 + (x - y) \Longrightarrow\]

\[\Longrightarrow верно.\]

\[(c + b) - a = (c - a) + b \Longrightarrow\]

\[\Longrightarrow неверно.\]

\[a - x - y = a - (x + y) \Longrightarrow\]

\[\Longrightarrow верно.\]

\[\boxed{\mathbf{19}.}\]

\[48 - (17 + a) = 48 - 17 - a =\]

\[= 31 - a\]

\[a - 34 - 22 = a - (34 + 22) =\]

\[= a - 56\]

\[116 - (16 + x) =\]

\[= 116 - 16 - x = 100 - x\]

\[387 - (98 + a) =\]

\[= 387 - 98 - a = 289 - a\]

\[a - 486 - 114 =\]

\[= a - (486 + 114) = a - 600\]

\[b - 77 - 123 =\]

\[= b - (77 + 123) = b - 200\]

\[\boxed{\mathbf{20}.}\]

\[52 + x + 33 = x + 52 + 33 =\]

\[= x + 85\]

\[86 + x + 14 = x + 86 + 14 =\]

\[= x + 100\]

\[74 + a + 13 = a + 74 + 13 =\]

\[= a + 87\]

\[c + 82 + 14 = c + 96\]

\[41 + 28 + a = 79 + a\]