1) 6а-(5а-(4а-3))=5а-3 6a-(5a-4a+3)=5a-3 6a-5a+4a-3-5a+3=0 (6a-5a+4a-5a)+(-3+3)=0 0+0=0 0=0 2) 5а-6(2-а)=12а-(а+12) 5a-12+6a=12a-a-12 11a-12=11a-12 11a-11a=-12+12 0=0 3) 4b+(b-(2-3b))+6-3b=5b+4 4b+(b-2+3b)+6-3b-5b-4=0 4b+b-2+3b+6-3b-5b-4=0 0=0