43.
1) а+(2b-3c)=a+2b-3c
2) a-(2b-3c)=a-2b+3c
3) a-(2b+3c)=a-2b-3c
4) -(a-2b+3c)=-a+2b-3c
44.
1) a+(b-(c-d))=a+(b-c+d)=a+b-c+d
2) a-(b-(c-d))=a-(b-c+d)=a-b+c-d
3) a-((b-c)-d)=a-(b-c-d)=a-b+c+d
4) a-(b+(c-(d-k)))=a-(b+(c-d+k))=a-(b+c-d+k)=a-b-c+d-k
45.
1) 3a-(a+2b)=3a-a-2b=2a-2b=2(a-b)
2) 5x-(2y-3x)=5x-2y+3x=8x-2y=2(4x-y)
3) 3m-(5m-(2m-1))=3m-(5m-2m+1)=3m-5m+2m-1=-1
4) 4a+(2a-(3a+2))=4a+(2a-3a-2)=4a+2a-3a-2=3a-2