Explications étape par étape:
n⁰6)
A = 4/3 × 9/14 = (2×2×3×3)/(3×2×7) = 6/7
B = 20/14 × (12/15 + 16/15)
= 20/14 × 28/15
= (4×5×2×14)/(14×3×5) = 8/3
C = (18/10 + 7/10) × 3/4 - 1/4
= 25/10 × 3/4 - 1/4
= (5×5×3)/(2×5×4) - 1/4
= 15/8 - 1/4 = 18/8 - 2/8 = 13/8
D = -12/7 - (4×5×7/(7 ×3×4)
= -12/7 - 5/3 =-36/21 - 35/21 = -71/31