Bonjour,
A = 3/5 – 2/3 × 9/4
A = 3/5 – 18/12 or 18/12 = 6/4 = 3/2
A = 3/5 – 3/2
A = 6/10 – 15/10
A = -9/10
B = (1 – 3/2)/(1 + 4/3)
B = (2/2 – 3/2) / (3/3 + 4/3)
B = (-1/2) / (7/3)
B = -1/2 × 3/7
B = -3/14
C = (10² × 15 × 10) / (5 × 10-¹)
C = (10³ × 15)/(5 × 10-¹)
C = 10³/10-¹ × 15/5
C = 10⁴ × 3
C = 30 000