Répondre :
A = 5/2-8/5x15/28
= 5/2-120/140
= 350/140-120/140=230/140 ou 23/14
B = (8/7-2)x(5/6-1)
= (8/7-14/7)x(5/6-6/6)
=-6/7x-1/6=6/42 ou 1/7
= 5/2-120/140
= 350/140-120/140=230/140 ou 23/14
B = (8/7-2)x(5/6-1)
= (8/7-14/7)x(5/6-6/6)
=-6/7x-1/6=6/42 ou 1/7