9 7/9 - 7 6/7 = 88/9 - 55/7 = (616 - 495) / 63 = 121/63 = 1 58/63
10 4/9 - 8 5/18 = 94/9 - 149/18 = (188 - 149) / 18 = 39/18 = 2 3/18 = 2 1/6
(1 3/20 + 3 5/12) + 4 7/20 = (23/20 + 41/12) + 4 7/20 = (69/60 + 205/60) + 4 7/20 = 274/60 + 87/20 = (274 + 261) / 60 = 535/60 = 8 55/60 = 8 11/12
4 - 3 5/9 = 4/1 - 32/9 = (36 - 32) /9 = 4/9
18 3/5 - 6 11/15 = 93/5 - 101/15 = (279 - 101) /15 = 178/15 = 11 13/15
2 9/70 + 5 3/14 - 1 9/35 = 149/70 + 73/14 - 44/35 = (149 + 365 - 88) /70 = 426/70 = 6 6/70 = 6 3/35