a) -(12+21-23)-(23-21+10)
=-12-21+23-23+21-10
=(-12-10)+(-21+21)+(23-23)
=-22+0+0=-22
b) (57-725)-(605-53)
=57-725-605+53
=(57+53)+(-725-605)
=110+(-1330)
=-1220
c) (55+45+15)-(15-55+45)
=55+45+15-15+55-45
=(55+55)+(45-45)+(15-15)
=110+0+0=11
Tích mk nha pn...
a. -(12 + 21 - 23 ) - ( 23 - 21 + 10 )
= - 12 - 21 + 23 - 23 + 21 - 10
= -22
b.
b.( 57 - 725) -(605-53)
= 57 - 725 - 605 + 53
= ( 57 + 53 ) - ( 725 + 605 )
= 110 - 1330 = -1220
c. ( 55 + 45 + 15 ) - ( 15 - 55 + 45 )
= 55 + 45 + 15 - 15 + 55 - 45
= 110