a) \(\left( { - 17} \right) + 5 + 8 + 17 \)
\(= \left[ {\left( {-17} \right) + 17} \right] + \left( {5 + 8} \right) \)
\(= 0 + 13 = 13\)
b) \({\rm{ }}\left( { - 4} \right) + \left( { - 440} \right) + {\rm{ }}\left( { - 6} \right){\rm{ }} + 440 \)
\(= \left[ {\left( { - 4} \right) + \left( { - 6} \right) + \left[ {\left( { - 440} \right) + 440} \right]} \right]\)
\(=-(4+6)+0\)
\(= (-10 ) + 0 = -10.\)
