4 2/7-3 2/9-5 5/7+1 1/3-5 1/9+2 3/7

=(4 2/7+2 3/7-5 5/7)-(3 2/9+5 1/9-1 3/9)=1 - 7 = -64 2/7+2 3/7=6 5/7 6 5/7 - 5 5/7 =13 2/9+5 1/9=8 3/98 3/9-1  3/9=71 - 7 = -6