Réponse :
bonjour
Explications étape par étape :
A=2/7 – 3/5
=10/35 -21/35
=-11/35
B=18/5 -6
=18/5 -30/5
=-25
C=7/6 - -2/9
=21/18 + 4/18
=25/18
D=-15/36 x -42/25 x28/21
= -3/6 x -7/5 x 4/3
=-1/3 x-7/5 x2
=14 /15
E=-28/45 +-35/12
=-1575/540 – 1911/540
=-1911/540
=-637/180
F=4/5 – 7/3x8/14
=4/5-1/3x4
=4/5 -4/3
=4/5 – 4/3
=12/15 – 20/15
=-8/15