aidez moi svp merci d avance

B = 1/4 + 5/6 = 1x6/4x6 + 5x4/6x4 = 6/24 + 20/24 = (6+20)/24 = 26/24
C = 12/5 - 3/5 = (12-3)/5 = 9/5
D = 3/4 - 2/3 = 3x4/4x3 - 2x4/3x4 = 12/12 - 8/12 = (12-8)/12 = 4/12
E = 5/7 x 2/7 = (2x5)/(7x7) = 10/49
F = 2/3 x 4/5 = (2x4)/(3x5) = 8/15