a) \(215+43+\left(-215\right)+\left(-25\right)\)
\(=\left[215+\left(-215\right)\right]+\left[43+\left(-25\right)\right]\)
\(=0+18\)
\(=18\)
b) \(\left(-312\right)+\left(-327\right)+\left(-28\right)+27\)
\(=\left[\left(-312\right)+\left(-28\right)\right]+\left[\left(-327\right)+27\right]\)
\(=\left(-340\right)+\left(-300\right)\)
\(=-640\)
a) \(215+43+\left(-215\right)+\left(-25\right)\)
\(=\left(215-215\right)+\left(43-25\right)\)
\(=0+18\)
\(=18\)
b) \(\left(-312\right)+\left(-327\right)+\left(-28\right)+27\)
\(=\left(-312-28\right)+\left(-327+27\right)\)
\(=\left(-340\right)+\left(-300\right)\)
\(=-640\)
