Réponse:
A = 3/8
B = 2/3
Explications étape par étape:
A = (1/3 × 6/5 - 3/10) × 15/4
= ((1×6)/(3×5) - 3/10) × 15/4
= (6/15 - 3/10) × 15/4
= ((6×2)/(15×2) - (3×3)/(10×3)) × 15/4
= (12/30 - 9/30) × 15/4
= 3/30 × 15/4
= (3×15)/(30×4)
= 45/120
simplification : 45÷15/120÷15 = 3/8
B = (8+2)/(7+2) × 3/5
= 3×(8+2)/5×(7+2)
= (3×10)/(5×9)
= 30/45
simplification : 30÷15/45÷15 = 2/3
