1. (1/4 + 1/8 - 3/2)×4/9 =
(2/8+1/8-12/8)×4/9 =
-9/8×4/9 = -1/2
2. [(3/3-2/3)⁻¹×(6/3-4/3)⁻¹×4/27+5/3]×3/7 =
[(1/3)⁻¹×(2/3)⁻¹×4/27+5/3]×3/7 =
(9/2×4/27+5/3)×3/7 =
(2/3+5/3)×3/7 =
7/3×3/7 = 1
3. [15/7×(15/5-1/5)×5/12-1/2]⁻¹+1/2 =
(15/7×14/5×5/12-1/2)⁻¹+1/2 =
(5/2-1/2)⁻¹+1/2 =
1/2 + 1/2 = 2/2 = 1
