Réponse :
A = 3/7 - 2/5 * 15/4
A = 3/7 - (2/5 * 3/2 * 5/2)
A = 3/7 - (3/2)
A = 6/14 - 21/14
A = -27/14
B= 1/8 - 7/12 / 7/6 + 7/12
B = 1/8 - (7/12 * 6/7) + 7/12
B = 1/8 - (1/2) + 7/12
B = 3/24 - 12/24 + 14/24
B = 5/24
C = (5/3 - 7/9) / (1/4 - 1/2)
C = (15/9 - 7/9) / (1/4 - 2/4)
C = (8/9) / (- 1/4)
C = - 32/9
Explications étape par étape
