bonsoir
inverse de 3/4 = 4/3 donc 1 : 3/4 = 1 x 4/3 = 4 /3
1 : - 2/5 = 1 x - 5/2 = - 5 /2
1 : - 4 /9 = 1 x - 9/4 = - 9 /4