a) 3/11 + 4/11 - 5/11 = 2/11
b) 4/3 + 5/4 - 5/6 = 16/12 + 15/12 - 10/12
= 21/12 = 7/4
c) 5/6 × 9/10 = 1/2 × 3/2 = 3/4
d) (2/3)³ = 2³/3³ = 8/27
