Tìm x biết `(x - 1000) + 600 + 100 - 600 - 100 = 1000`

`( x - 1000 ) + 600 + 100 - 600 - 100 = 1000`

`x - 1000 + 600 + 100 - 600 - 100 = 1000`

`x - 1000 + (600 - 600) + (100 - 100) = 1000`

`x - 1000 + 0 + 0 = 1000`

`x - 1000 = 1000`

`x = 1000 + 1000`

`x = 2000`