A = 14/18 - 6/18 + 15/18 = (14-6+15)/18 = 21/18 = 7/6 = 1' 1/6
B= 19/15 + 270/45 - 15·7/180 = 19·12/180 +270·4/180 - 105/180=
= (228+1080 - 105)/180 =1203/180 = 401/60 = 6' 41/60
285/28 + ((12-3)/14= 285/28 + 3/14 = (285 - 2.3)/28 = 279/28 = 9' 27/28