1) 13/6 и 28/9 = (НОЗ: 18) = 13*3/18 и 28*1/18 = 39/18 и 28/18
2) 30/7 и 109/21 = (НОЗ: 21) = 30*3/21 и 109*1/21 = 90/21 и 109/21
3) 14/3 и 5/2 = (НОЗ: 6) = 14*2/6 и 5*3/6 = 28/6 и 15/6
4) 38/15 и 17/12 = (НОЗ: 60) = 38*4/60 и 17*5/60 = 152/60 и 85/60