Bài 2,
a, (x+17)-(24+35)
= x+17-24-35
= x-42
b, (-32)-(y+20)+20
= -32-y-20+20
= -y-32
Bài 3,
a,( 3567-214)-3567
=( 3567-3567)-214
=-214
b, (-2017)-(28-2017)
= (-2017+2017)-28
=-28
c, -(269-357)+(269-357)
=(-269+269)+ (357-357)
= 0
d, (123+345)+(456-123)-(2017-(-345))
=123+345+456-123-2017-345
= (123-123)+(345-345)+456-2017
= 0+0+456-2017
= -1561
Chúc bạn học tốt !
