(2/35+3/28)+1/28 = 2/35 + 3/28 + 1/28 = 2/35 + 4/28 = 2/35 + 1/7 = 2/35 + 5/35 = 7/35 = 1/5
(5/24+11/60)+(13/60+1/24) = 5/24 + 11/60 + 13/60 + 1/24 = 5/24 + 1/24 + 11/60 + 13/60 = 6/24 + 24/60 = 1/4 + 2/5 = 5/20 + 8/20 = 13/20
