= 12 - 21 + 23 - 23 + 21 - 10
= ( 12 - 10) + ( 23 - 23 ) + ( 21 - 21)
= 2 + 0 + 0
= 2
-(12+21-23)-(23-21+10)= -12-21+23-23+21-10=-22
Ủng hộ nhaa bn
-(12+21-23)-(23-21+10)
= - 12-21+23-23-21+10
= (-12+10)+(21-21)+(23-23)
= -2+0+0
=-2
-(12+21-23)-(23-21+10)
=-12-21+23-23+21-10
=[(21+21]+(23-23)-(12+10)
=0+0-22
=-22