Câu 1 :
c) $35.18-5.7.28$
$=35.18-35.28$
$=35.(18-28)$
$=35.(-10)$
$=-350$
d) $24(16-5)-16(24-5)$
$=24.16-5.24-16.24+16.5$
$=5.(-24+16)$
$=5.(-8)$
$=-40$
Câu 2 :
1) $(a-b+c)-(a+c)=-b$
2) $(a+b)-(b-a)+c=2a+c$
3) $-(a+b-c)+(a-b-c)=-2b$
4) $a(b+c)-a(b+d)=ab+ac-ab-ad=ac-ad=a(c-d)$