aide pr exercice numero 1 svpp !!!

A = - 45/26 : - 9/13
A = - 45/26 x - 13/9
A = 585/234
A = 117 x 5 / 117 x 2
A = 5/2

B = (1/3 - 5/4) : 33/4
B = (1 x 4 / 3 x 4 - 5 x 3 / 4 x 3) : 33/4
B = (4/12 - 15/12) : 33/4
B = - 11/12 : 33/4
B = - 11/12 x 4/33
B = - 44/396
B = 44 x - 1 / 44 x 9
B = - 1/9