Bonsoir
N°53
A = 12/5 -3/5 x 7/9 = 12/5 - 21/45 = 108/45 - 21/45 = 87/45 = 29/15
B = (2/3-3) : 1/9 = (2/3 -9/3) : 1/9 = -7/3 x 9 = - 63/3 = -21
N°54
A = 5/3-7/3x9/4 = 5/3 -63/12 = 20/12 -63/12 = -43/12
B 3 -3/2 : (4/3 x 7) = (6/2 -3/2) : 28/3 = 3/2 x 3/28 = 9/56 = 8