1) 18/30 = 3/5, 15/18 = 5/6; 18/30 и 25/30; 2) 28/40 = 7/10, 10/45 = 2/9, 63/90 и 20/90; 3) 49/105 = 7/15, 27/36 = 3/4, 56/120 и 90/120; 4) 60/90 = 2/3, 15/50 = 3/10, 20/30 и 9/30; 5) 10/20 = 1/2, 8/24 = 1/3, 9/45 = 1/5, 15/30, 10/30 и 6/30; 6) 22/44 + 1/2, 24/30 = 4/5, 27/36 = 3/4, 10/20, 16/20 и 15/20.