1) 2/9 + 7/11 - 10/99 = (2 × 11 + 7 × 9 - 10 × 1)/99 = 22/99 + 63/99 - 10/99 = 75/99 = 25/33
2) 3 5/12 + 9 1/6 - 5 1/18 = 41/12 + 55/6 - 91/18 = (41×3 + 55 × 6 - 91×2)/36 = 123/36 + 330/36 - 182/36 = 271/36 = 7 19/36
3) 18/85 + 6 5/63 - 7/18 = 18/85 + 383/63 - 7/18 = (18 × 126 + 383 × 170 - 7 × 595)/10710 = 2268/10710 + 65110/10710 - 4165/10710 = 63213/10710 = 21071/3570 = 5 3221/3570
4) 5 2/3 + 11 7/12 - 4 3/4 = 17/3 + 139/12 - 19/4 =(17 × 4 + 139 × 1 - 19 × 3)/12 = 68/12 + 13912 - 57/12 = 150/12 = 25/2 = 12 1/2
5)9 2/5 + 3/8 - 4 3/20 = 47/5 + 3/8 - 83/20 =(47 × 8 + 3 × 5 - 83 × 2)/40 = 376/40 + 15/40 - 166/40 = 225/40 = 45/8 = 5 5/8
6)10 1/12 + 2 5/36 - 2 7/72 = 121/12 + 77/36 - 151/72 = (121 × 6 + 77 × 2 - 151 × 1)/72 = 726/72 + 154/72 - 151/72 = 729/72 = 81/8 = 10 1/8
