Bonjour !
A = (9/7 - 3/4) * 5/2
A = [(9*4)/(7*4) - (3*7)/(4*7)] * 5/2
A = (36/28 - 21/28) * 5/2
A = 15/28 * 5/2
A = (15*5) / (28*2)
A = 75/56
B = (2/5 - 1/10) / (2/3 + 1/10)
B = [(2*2)/(5*2) - 1/10] / ((2*10)/(3*10) + (1*3)/(10*3)]
B = (4/10 - 1/10) / (20/30 + 3/30)
B = 3/10 / 23/30
B = 3/10 * 30/23
B = (3*30) / (10*23)
B = 90/230
B = 9/23
C = 2/9 - 3/4 * 5/2
C = 2/9 - (3*5) / (4*2)
C = 2/9 - 15/8
C = (2*8)/(9*8) - (15*9)/(8*9)
C = 16/72 - 135/72
C = -119/72
J'espère t'avoir aidé. Bon courage !
