1) 4а-(3+(5а-4)) 2) 7а-(4а+(8а-1)) 3) 5+(3а(6-7а))

 4а-(3+(5а-4)) =4а-(3+5а-4)=4а-3+5а-4=а-17а-(4а+(8а-1))=7а-(4а+8а-1)=7а-4а+8а-1=5а-15+(3а(6-7а))=5+18а-21а²