Soit A=7/4-3/4*8/9 et B=(1-2/3)(1+2/3) Calcuer Aet B et donner chaque résultat sous forme d'une fraction irréductible

A = 7/4 - 3/4 x 8/9
A = 7/4 - 24/36
A = 7 x 9 / 4 x 9 - 24/36
A = 63/36 - 24/36
A = 39/36
A = 3 x 13 / 3 x 12
A = 13/12

B = (1 - 2/3) (1 + 2/3)
B = (1 x 3 / 1 x 3 - 2/3) (1 x 3 / 1 x 3 + 2/3)
B = (3/3 - 2/3) (3/3 + 2/3)
B = 1/3  * 5/3
B = 5/9