5/7 x 3/5 = 15/35 = 3/7
5/6 - 3/8 - 1/12 = 20/24 - 9/24 - 2/24 = 9/24 = 3/8
21/20 - 3/8 - 1/5 = 42/40 - 15/40 - 8/40 = 19/40
13/15 - (1/5 + 1/6) = 13/15 - (6/30 + 5/30) = 13/15 - 11/30 = 26/30 - 11/30 = 15/30 = 1/2
5/7 x 3/5 = 15/35 = 3/7
5/6 - 3/8 - 1/12 = 20/24 - 9/24 - 2/24 = 9/24 = 3/8
21/20 - 3/8 - 1/5 = 42/40 - 15/40 - 8/40 = 19/40
13/15 - (1/5 + 1/6) = 13/15 - (6/30 + 5/30) = 13/15 - 11/30 = 26/30 - 11/30 = 15/30 = 1/2