A) 8/18 - 8/27 = 4/9 - 8/27 = 12/27 - 8/27 = 4/27
б) 7/16 - 5/24 = 21/48 - 10/48 = 11/48
в) 2/11 - 1/12 = 24/132 - 11/132 = 13/132
г) 12/13 - 15/26 = 24/26 - 15/26 = 9/26
д) 9/28 - 11/35 = 45/140 - 44/140 = 1/140
е) 39/40 - 19/28 = 273/280 - 190/280 = 83/280