1) - 1 ( 1/2 ) + 2 ( 2/3 ) = - 1 ( 3/6 ) + 2 ( 4/6 ) = 1 ( 1/6 ) ;
2) 1 ( 1/6 ) : 3 ( 3/4 ) = ( 7/6 ) : ( 15/4 ) = 14/45 ;
3) ( 14/45 ) - ( 2/5 ) = ( 14/45 ) - ( 18/45 ) = - 4/45 ;
4) - ( 4/45 ) : - 8 ( 8/9 ) = - ( 4/45 ) : - (80/9 ) = 1/100 ;
5) ( 1/100 ) + ( 1/4 ) = ( 1/100 ) + ( 25/100 ) = 26/100 = 0,26
Ответ 0,26