Réponse :
bonjour,
A = 5/7 + 2×4 /7×5
A =5/7 + 8/35
A = 5×5 + 8 / 35
A = 25 + 8 /35
A = 33/35
B = 1×3 + 1×5 / 15 ÷ 2×4 - 3×5 / 12
B = 3 + 5 /15 ÷ 8 - 15 /12
B = 8/5 ÷ - 7/12
B = 8/5 × - 12/7
B = - 96/35
C = - 8/5 + - 2/3 + 5/2
C = - 8×3×2 + - 2×5×2 + 5× 5× 3 / 5×3×2
C = - 48 - 20 + 75 / 30
C = 7/30
Explications étape par étape :