№269.
а) (- 1 4/11 ) + ( - 1 2/11) - ( - 1 4/11) =
= (-1 4/11) + (-1 2/11) + 1 4/11 =
= (- 1 4/11 + 1 4/11 ) - 1 2/11 =
= - 1 2/11
б) 2 5/8 + (- 2 1/8) - (- 1 1/2) =
= 4/8 - (- 1 1/2) = 1/2 + 1 1/2 = 2
в) - 3 1/2 - ( - 2 5/12) + 1 1/12 =
= - 3 6/12 + 2 5/12 + 1 1/12 =
= - 3 6/12 + 3 6/12 =0
г) - ( - 4 3/16 ) + (- 2 1/2) + 3 5/16 =
= 4 3/16 - 2 8/16 + 3 5/16 =
=( 4 3/16 + 3 5/16) - 2 8/16=
= 7 8/16 - 2 8/16 = 5