A) 5 ( 4/5 ) - 2/5 = 5 ( 2/5 ) ;
Б) 7 ( 8/9 ) - 2 ( 6/9 ) = 5 ( 2/9 ) ;
В) 13 ( 9/11 ) - 2 = 11 ( 9/11 ) ;
Г) 6 - 2 ( 13/17 ) = 5 ( 17/17 ) - 2 ( 13/17 ) = 3 ( 4/17 ) ;
Д) 9 ( 7/12 ) - 3 ( 11/12 ) = 8 ( 19/12 ) - 3 ( 11/12 ) = 5 ( 8/12 ) = 5 ( 2/3 ) ;
Е) 6 ( 1/5 ) - 5 ( 3/5 ) = 5 ( 6/5 ) - 5 ( 3/5 ) = 3/5