2-(6 7/8 -7 1/3):3/4
2-(6 7/8-7 1/3) : 3/4= 2-11/24:3/4=2-11/18=1 7/18
6 7/8-7 1/3= -9/24 -9/24 :3/4= -1/2 2- (-1/2) = 2 1/2 = 2,5