Помогите пожалуйста номер 520
3/10 = 10/3 4/5 = 5/4 13/15 = 15/13 6/25 = 25/6 21/28 = 28/21 5/3 = 3/5 35/44 = 44/35 200/11 = 11/200 25= 25/1 = 1/25 71= 71/1 = 1/71 321= 321/1 = 1/321