ГДЗ по математике 5 класс Алышева Тысяча Задание 40

\[\boxed{\mathbf{40.}}\]

\[x - 100 = 400\]

\[x = 400 + 100\]

\[x = 500.\]

\[x + 100 = 400\]

\[x = 400 - 100\]

\[x = 300.\]

\[x + 100 = 1000\]

\[x = 1000 - 100\]

\[x = 900.\]

\[100 + x = 300\]

\[x = 300 - 100\]

\[x = 200.\]

\[x - 100 = 700\]

\[x = 700 + 100\]

\[x = 800.\]