2) a-(2b-3c)=а-2b+3c

4) -(a-2b+3c)= -a+2b-3c

2)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

2)5x-(2y-3x)=5x-2y+3x=8x-2y

4)4a+(2a-(3a+3))=4a+2a-3a-3=3a-3