a) 7/8 + 3/4 = 7/8+ 6/8 = 13/8
b) 31/8 + 7/3 = 93/24 + 56/24 = 149/24
c) 5/8 + 7/12 = 15/24 + 14/24 = 29/24
d) 7/9 + 5/11 = 77/99 + 45/99 = 122/99
e) 5/6 + (1/6 + 7/8) = 5/6 + (4/24+21/24) = 5/6 + 25/24 = 20/24 + 25/24 = 45/24
f) 3/11 + (5/11 + 3/11) = 3/11 + 8/11 = 11/11 = 1
g) 5/6 +1/3 + 4/8 = 20/24 + 8/24 + 12/24 = 40/24 = 20/12 = 10/4 = 5/2
h) 5/12 + 4/5 + 5/8 = 50/120 + 96/120 + 75/120 = 221/120