1 3/4 + ( - 1 / 2 )=1 3/4-2/4=1 1/4
5 2/9+(-1/3)=5 2/9-3/9=5-1/9=4 8/9
4 3/8+(-1/4)=4 3/8-2/8=4 1/8
5 1/2+(-8 5/6)= 5 3/6-8 5/6=-3 2/6=-3 1/3
4 1/3+(-7 5/9)=4 3/9-7 5/9=-3 2/9
