-1/3-2/3
-5/6-1/3
-6 1/2-3 5/7

-1/3-2/3=-(1/3+2/3)=-3/3=-1-5/6-1/3=-(5/6+1/3)=-7/6=-1 1/6-6 1/2-3 5/7=-(6 1/2+3 5/7)=-9 17/14=-10 3/14