Дроби к знаменателю: 7/20 и 1/15, 7/13 и 2/11, 3/22 и 2/33, 7/60,13/540 и 9/20, 52/105,7/95 и 61/63 заранее говорю .

7/20 = 21/60 1/15 = 4/60
7/13 = 77/143 2/11 = 26/143
3/22 = 9/66 2/33 = 4/66
7/60 = 63/540 13/540 9/20 = 243/560
52/105 = 2964/5985 7/95 = 441/5985 61/63 =5795/5985