(1\2)*(3 1\3 - 2 8\9)
(1/2*4/9)=(4/18)=(2/9)
(1/2)×(3 1/3 - 2 8/9)=(1/2)×(3 3/9 - 2 8/9)=(1/2)×(2 12/9 - 2 8/9)=1/2 × 4/9= 2/9