2/3 : 5/7, 1/4 : 1/2 , 2/5 : 2/3 3/4 : 1/2 , 5/6 : 7/12

1) 2/3 : 5/7 = 2/3 * 7/5 = 14/15 2) 1/4 : 1/2 = 1/4 * 2/1 = 2/4 = 1/2 3) 2/5 : 2/3 = 2/5 * 3/2 = 6/10 = 3/5 4) 3/4 : 1/2 = 3/4 * 2/1 = 6/4 = 3/2 5) 5/6 : 7/12 = 5/6 * 12/7 = 60/42 = 10/7