giải thích a,17-229+17-25+229
=17+17+(-229+229)
=34+0=34
b,125-679+145-125+679
=(125-125)+(-679+679)+145
=0+0+145=145
c,3567-214-3567
=(3567-3567)-214=0-214=-214
d,-2017-28+2017=(-2017+2017)-28=0-28=-28
e,-269+357-269+357
=-269-269+357+357
=-538+714
=176