a) 4/15 + 9/10 + 11/15 = 15/15 + 9/10 = 1/1 + 9/10 = 10/10 + 9/10 = 19/10
b) 17/16 + 12/13 + 15/16 + 14/13 = 32/16 + 26/13 = 2 + 2 = 4
c) 5/8 + 7/18 + 3/8 + 11/18 + 1/8 = 8/8 + 18/18 +1/8 = 1 + 1 + 1/8 = 2 + 1/8 =
=16/8 + 1/8 = 17/8
d) 8/14 + 5/14 + 1/3 + 1/14 + 2/3 = 14/14+ 3/3 = 1 + 1 = 2