Répondre :
B =( 5/8)/(4/3) . Pour dicviser 2 fractions, tu multiplies la 1ere par l'inverse de la seconde. Tu as donc : 5*3/8*4 = 15/32
C = (3/12)/(4/6) = 3/12*6/4 = 18/48 = 9/24 = 3/8
D = (7/9)/(19/21) = 7*21/9*19 = 147/171 = 49/57
E = (13/13)/(1/15) = 13*15/13*1 = 195/13 = 15