20 + 30 + (-20) + (-30) = 100
100 + 230 + 600 + (-100) + (-230) = 600
20+30+(-20)+(-30)+100
=[20+(-20)]+[30+(-30)]+100
=0+0+100
=100.
100+230+600+(-100)+(-230)
=[100+(-100)]+[230+(-230)]+600
=0+0+600
=600.
20 + 30 +(- 20) + (-30 )+100=20 +(-20)+30 +(-30)+ 100=0 +0+100=100
100+230+600+(-100)+(-230)=100+(-100)+230+(-230)+600=0+0+600=600
A, 20 + 30 +(-20) +(-30) +100
=[(-20) + 20] +[(-30) +30] +100
=0 + 0 + 100
=100
B,100 +230 +600 +(-100) +(-230)
=[100+(-100)] +[230 +(-230)] +600
=0 + 0 +600
=600
HAPPY NEW YEAR
TK NHA BẠN
20+30+(-20)+(-30)+100
= [ 20 + ( -20 ) ] + [ 30 + ( -30 ) ] + 100
= 0 + 0 + 100
= 100
100 + 230 + 600 + ( -100 ) + ( -230 )
= [ 100 + ( -100 ) ] + [ 230 + ( -230 ) ] + 600
= 0 + 0 + 600
= 600