Bonjour,
E = (3/5 - 5/3) : 7/2 - (5 - 2/3)
E = (3 x 3 / 5 x 3 - 5 x 5 / 3 x 5) : 7/2 - ( 5 x 3 / 1 x 3 - 2/3)
E = (9/15 - 25/15) : 7/2 - (15/3 - 2/3)
E = - 16/15 : 7/2 - 13/3
E = - 16/15 x 2/7 - 13/3
E = - 32/105 - 13/3
E = - 32/105 - 13 x 35 / 3 x 35
E = - 32/105 - 455/105
E = - 487/105