1)
-(x+y) = - ( -1/3 + 0,5 ) = - ( - 1/3 + 1/2 ) = - ( (-2+3)/6 ) = -1/6
2) -(х-у) = - ( -1/3 - 0,5 ) = - ( - 1/3 - 1/2 ) = - ( (-2-3)/6 ) = 5/6
3) -(-х+у) = - ( 1/3 + 0,5 ) = - ( 1/3 + 1/2 ) = - ( (2+3)/6 ) = - 5/6
4) -(-х-у) = - ( 1/3 - 0,5 ) = - ( 1/3 - 1/2 ) = - ( (2-3)/6 ) = +1/6