Решебник по математике 5 класс Виленкин Часть 1, 2 Часть 1. Параграф 2. Сложение и вычитание натуральных чисел Задание 205

\[\boxed{\mathbf{2}\mathbf{.}\mathbf{205}}\]

\[\textbf{а)}\ (x + 27) - 12 = 42\]

\[x + 27 = 42 + 12\]

\[x + 27 = 54\]

\[x = 54 - 27\]

\[x = 27.\]

\[Проверка:\]

\[(27 + 27) - 12 = 42\]

\[54 - 12 = 42\]

\[42 = 42.\]

\[\textbf{б)}\ 115 - (35 + y) = 39\]

\[115 - 35 - y = 39\]

\[80 - y = 39\]

\[y = 80 - 39\]

\[y = 41.\]

\[Проверка:\]

\[115 - (35 + 41) = 39\]

\[115 - 35 - 41 = 39\]

\[80 - 41 = 39\]

\[39 = 39.\]

\[\textbf{в)}\ (z - 35) - 64 = 16\]

\[z - 35 = 16 + 64\]

\[z - 35 = 80\]

\[z = 80 + 35\]

\[z = 115.\]

\[Проверка:\]

\[(115 - 35) - 64 = 16\]

\[80 - 64 = 16\]

\[16 = 16.\]

\[\textbf{г)}\ (28 - t) + 35 = 53\]

\[28 - t = 53 - 35\]

\[28 - t = 18\]

\[t = 28 - 18\]

\[t = 10.\]

\[Проверка:\]

\[(28 - 10) + 35 = 53\]

\[18 + 35 = 53\]

\[53 = 53.\]

\[\textbf{д)}\ 73 - (x + 26) = 19\]

\[x + 26 = 73 - 19\]

\[x + 26 = 54\]

\[x = 54 - 26\]

\[x = 28.\]

\[Проверка:\]

\[73 - (28 + 26) = 19\]

\[73 - 54 = 19\]

\[19 = 19.\]

\[\textbf{е)}\ 55 - (z - 45) = 62\]

\[55 - z + 45 = 62\]

\[100 - z = 62\]

\[z = 100 - 62\]

\[z = 38.\]

\[Проверка:\]

\[55 - 38 + 45 = 62\]

\[17 + 45 = 62\]

\[62 = 62.\]