а) 5/9 + 1/6 = 10/18 + 3/18 = 13/18
б) 5/8 - 3/4 = 5/8 - 6/8 = -1/8
в) 4/7 * 14/15 = 56/105 = 8/15
г) 20/27 : 5/6 = 20/27 * 6/5 = 120/135 = 8/9
д) 2/3
а) 5/9 + 1/6 = 10/18 + 3/18 = 13/18
б) 5/8 - 3/4 = 5/8 - 6/8 = -1/8
в) 4/7 * 14/15 = 56/105 = 8/15
г) 20/27 : 5/6 = 20/27 * 6/5 = 120/135 = 8/9
д) 2/3