a +1982 +182 + (-1982) -172
= a + [1982+ (-1982) ] + [182 + (-172)]
=a + 0 + 10
=a + 10
= a + (1982+-1982)+(182+-172)
= a + 0 + 10
= a + 10
\(\Rightarrow a+\left[1982+\left(-1982\right)+\left(182-172\right)\right]\)
\(\Rightarrow a+10\)
a +1982 +182 + (-1982) -172
= a + [1982+ (-1982) ] + [182 + (-172)]
= a + 0 + 10
= a + 10