\(\left[\left(-457\right)+257\right]+\left[\left(-123\right)+123\right]\)
\(=\left(-200\right)+0=-200\)
\(\left(-457\right)+\left(-123\right)+123+257\)
\(=\left[\left(-123\right)+123\right]+\left[\left(-457\right)+257\right]\)
\(=0+\left(-200\right)=-200.\)