а)x+(3-x) =x+3-x=3
б)2a-(a-(5+3a))=2a-a+(5+3a)=a+5+3a=4a+5
в)5ab-(ab+(-5ab-(2ab-1)))=5ab-(ab+(-5ab-2ab+1)))=
5ab-(ab+(-7ab+1)))=5ab-(ab-7ab+1))=
=5ab-(-6ab+1)=5ab+6ab-1=11ab-1
а)x+(3-x) =x+3-x=3
б)2a-(a-(5+3a))=2a-a+(5+3a)=a+5+3a=4a+5
в)5ab-(ab+(-5ab-(2ab-1)))=5ab-(ab+(-5ab-2ab+1)))=
5ab-(ab+(-7ab+1)))=5ab-(ab-7ab+1))=
=5ab-(-6ab+1)=5ab+6ab-1=11ab-1